Its night time and Seira and Senku are hammering away gathering Sulfur. While Taiju and Yuzuriha are bathing in the hot springs.
"Yuzuriha.. I should tell you about what happened while you were petrified. 3,700 years ago, when I called you to the camphor tree.. Taiju said. Yuzuriha blushed remembering the bold moves Taiju displayed to her.
"What were you about to say that day?" She asked.
"Yuzuriha, for the whole time I was Petrified, I thought about finishing what I was saying. For hundreds of years, thousands of years... But here, in the stone world, with nowhere to run, I wouldn't feel right as a man telling you." Taiju said.
"Sorry! I'm sure you have no idea what I'm talking about ..." Taiju said.
"No, I do." She said
"We have to bring back civilisation. Once we save humanity, will you let me finish what I was saying 3,700 years ago, Yuzuriha?" Taiju asked.
"Okay, got it. We'll bring the world back. I'm sure of it." She said.
Seira who was listening. I've waited for thousands of years and this is what I get. Don't fuck with me Taiju teme screw you and your chivalry! She thought.
After Taiju and Yuzuriha were done bathing.
"Senku it's our turn to bath." Seira said and her brother flinched. "What?, why? I'm still collecting my sulfur." He whined.
"Yes, yes now come on, I cant have you dealing with sulfur and not take a bath after. Its unhygienic. She said dragging a struggling Senku to the hot springs. "No! Let me go!" He said struggling to get out of his sister's hold.
*The next day*
"We have the three materials we need to make gun powder." Senku said.
"Yay!" Seira cheered.
"We have them already?" Taiju asked.
"All we need to do now is mix it. It's time for out happy gun powder cooking session!" Senku said.
*In Senku's kitchen *
Senku and yuzuriha are behind a kitchen table, while Taiju holds a camera and Seira has earphones on and holding a clipboard.
"Ingredient number one for gunpowder... Sulfur,which we can get plenty of at this hot spring. Senku said as Yuzuriha pours the sulfur in a bag.
"Number two... Charcoal. We can get all we need buy burning wood." He said throwing bars of charcoal in the bag.
*out of senku's kitchen *
"Number three, the last but most difficult: potassium nitrate. It'll take a hell of a long time to make this stuff, so...kukuku I've already made some to save us time!" He said, the last part a bit animatedly.
"I feel like I've heard the word 'nitrate' somewhere... Taiju said. "Nitrica acid! Miracle water! You got it from the cave?" He realized.
"You're right for once,simpleton. 10 billion points for you." Senku said pouring the potassium nitrate into to bag. "Potassium nitrate, sulfur,and charcoal all go in the mix, and a pinch of sugar that Seira made as a secret ingredient gives it a little more oomph." He said mixing the contents in the bag.
"This is glucose that I made from grapes." Senku added. "Finally, pound it until it's packed solid." Senku said about to smash it with a log when Taiju comes in with a boulder in his hands.
"Pound it, huh?! Leave the heavy lifting to me! Taiju said.
Yuzuriha stops him. "Are you sure that's a good idea? You might be strong enough to make it spark and go boom! Like flint ." She said.
"Nah, you won't get any Sparks by hitting stone with stone." Senku said.
"Really?" Yuzuriha asked.
"I hope you're right about this Senku." Seira said.
Taiju proceeds with the boulder in his hands and starts pounding. "Oh you're right." He said.
"Flint is more than just stone. It need to have metal in it to make sparks. Hot springs, Volcanoes, iron pyrite... Iron pyrite?! Wai-"
But it's too late as Taiju is already going for it. After hitting the bag he picks it up and the gang sees sparks coming out of the bag. The gangs makes a break for it before the bag finally explodes for force of the blast sends them flying.
Seira lands on her feet but skids across the ground in the process. She gets up. "You won't get any sparks huh? " She said glaring at her brother.
When the rest gets up Senku gets excited. "No problem! Our gun powder cooking was a huge success!" He said.
"I had no idea gunpowder was so powerful." Yuzuriha said.
"Yeah, there've been plenty of accidents where students were experimenting with it and got their limbs blown off. It can easily be lethal." Senku said.
Seira got angry and grabbed her brother by his collar. "Got their limbs blown off huh? Wow, we almost got our limbs blown off. It's also lethal. Hey Senku, who is gonna take responsibility I wonder?" She said glaring at her brother.
Senku was sweating bullets. "Calm down! It didn't happen so we're fine. My bad! So put me down!" He said and Seira puts him down satisfied with that.
"We're going to attack Tsukasa-kun with this?" Yuzuriha asked.
"No, we're going to make a deal. Tsukasa isn't a mindless killer. Taiju remember what he said when you went at him? In other words, in the right circumstances, we can negotiate with him. As long as we have a gunpowder weapon, we have leverage." Senku said.
Taiju and Yuzuriha sigh in relief. Seira didn't join them instead she crossed her arms and gave a side glance to her brother.
But if negotiations with Tsukasa fall through, then we'll have to ...
Tsukasa is running through the forest.
If Senku has already made gunpowder, I'll have to...
Kill him. Senku and Tsukasa thought.
The gang are pouring water on the fire in hopes to get rid of the smoke.
"All right, it's gotten weaker." Taiju said.
"If Tsukasa's after us, there's a 10 billion percent chance he'll find us. Senku said.
Yuzuriha and Seira see something in the distance. "Senku-kun, Taiju-kun..." yuzuriha calls out. They turn around and are shocked to see a smoke signal in the distance.
"Tsukasa-kun?!" Yuzuriha said worried.
"No, its coming from the opposite direction. Besides, Tsukasa has no reason to reveal his location." Senku said.
"What is it, then? A forest fire?" Taiju asked.
"No, it's too well-timed to be a coincidence. It was clearly raised in response to our smoke." Seira said.
"You mean..." Yuzuriha said.
"Yeah, this is exhilarating. There's someone else in the stone world." Senku said.
"More people?" Taiju said.
"We have to finish putting out the fire." Yuzuriha said.
"Oh, that's right. Taiju said following after her.
"No, hang on." Senku said making the two stop. "As far as we know, that explosion could have been from a volcano. We need to signal them even more before they leave." Senku said.
"I see!" Taiju said.
"But if Tsukasa-kun is after us..." yuzuriha said.
"This could put us at major risk of being found. Senku are sure you want to do this remember we're being hunted." Seira said.
"Then we'll be doing him the courtesy." Senku said. But the others are unsure.
The least logical part ic me, my gut, is talking to me. If we start a fire now... which do I choose? Safety? The future?
"What do we do, Senku? Put it out? Or light it?" Taiju asked.
"Light it. Fire the smoke signal!" Senku said.
Explosions echoed through the forest. Pieces of wood are being thrown into the fires.
"We're running out of gun powder. Throw in anything that'll burn!" Senku said and the others scatter to look for things to burn.
Even Coco helped and found some twigs that she could carry and threw them in the fire. Senku was impressed with the little rodent.
"Hang on! I'll go get some wood!" Taiju said.
Seira and Yuzuriha followed behind him.
It's a double-edged smoke signal. We're letting everyone in the vicinity know where we are. If Tsukasa knows about our plan to make gunpowder... Senku thought.
Tsukasa is running through the forest closing in. Senku is trying to make gunpowder. The shells told me as much.
He remembers Senku saying that there were four uses to calcium carbonate and another memory of him saying they were three.
Senku hid one because he thought I could be a threat. Which means... The fourth important use for sea shells is weapons of science. It's easy to imagine. For example, mass production of potassium nitrate which is used in gunpowder.
Tsukasa now close to the hill sees smoke coming out. That's it. Senku was already thinking ahead to a future in which he'd use gunpowder to fight me.
Yuzuriha is gathering twigs at the bottom of the hill when Tsukasa came in from behind her holding a blade to her neck cutting her ribbon off.
Senku kneels beside the fire and Tsukasa appears holding yuzuriha with a blade to her neck.
"If weapons of science enter the scene, I won't be the most powerful anymore." You look like you're about to throw a tantrum, Tsukasa." Senku said.
The flying squirrel saw everything in the bushes. She is shivering with fear but gets ahold of herself and runs to get Seira to warn her of trouble and to get here quickly before something bad happens.
"You could put it that way. If you make weapons of science and revive the older generations, they'll begin fighting over established interests, and we'll be right back to a tainted world. I don't mind getting my hands dirty in order to stop that." Tsukasa said. (AN:When I was watching this part. I was like Bruh😑 new world ,new rules. Why so negative)
"So now you have to kill science man Senku here,huh? Americawould be moved to tears by your merciful death sentence." Senku said.
"Yeah. But first, would you mind giving me the recipe for the petrification revival fluid?" Tsukasa said holding the blade closer to Yuzuriha's neck.
"Sorry, but I'm not as merciful as you are. I can only look at things logically. I dont care one millimeter what you do with that woman. There are plenty of females around-" Senku was stopped when he saw Tsukasa cut of Yuzuriha's hair clean off her shoulders.
"Don't try to negotiate, Senku. You never buried Yuzuriha. Your best move would have been to bury Yuzuriha somewhere far away while she was petrified. That way, she'd never be taken hostage.
There's no way you couldn't have thought of something that even I did. But you didn't do it. Was it for Taiju? Or for Yuzuriha? No, it was for both of them." Tsukasa said. Yuzuriha was surprised and Senku was getting worried.
"You call yourself logical yourself, but you have friends that are precious to you. I have many admirers but I have no one I'd call precious. That's why I win, Senku. That's why I won." Tsukasa said.
"I actually appreciate that." Yuzuriha said laughing a bit. "Washing my hair is a pain in this world." She said grabbing the blade in Tsukasa's hand and putting in close to her neck.
"Don't tell him, Senku-kun. So long as he doesn't have the recipe for the revival fluid, Tsukasa cant kill you." She said bringing the blade closer. " I don't mind. But you have to survive so that you can secure everyone's future. I doubt that with you gone Seira could do it without you, she needs you Senku-kun." She said.
Senku takes a breath. "The revival fluid is a compound of nitric acid and alcohol. Filter the miracle water from the cave, and mix it with alcohol that's been distilled up to as close to 96% as you can get it. The ratio is 30% miracle water to 70% alcohol. If you're off by so much as a few percent, the reaction won't happen, so fine-tune it using a petrified swallow feather. " Senku said finishing off the recipe for the revival fluid resulting in Yuzuriha crying because Senku sacrificed the recipe and his life for her.
"Thank you, Senku. I no longer have a reason to let you live." Tsukasa said
Taiju is picking up sticks. When he looks up and sees three smoke signals.
"Three smoke signals. They must be responding to the three shots we fired with the gunpowder! There's no mistake! There are people! Senku! Yuzuriha!" Taiju yelled.
A blonde haired blue eyed girl is playing with the fire keeping it lit. "Three." She said looking at the flame.
Tsukasa throws Yuzuriha to the ground and jumped in front of Senku and began to approach him.
" Will you promise not to do that." Tsukasa asked.
"What the hell are you talking about? Why would I ever keep a promise like-" Senku said but was interrupted by Tsukasa. "No, you would never lie. Not to science. Will you promise here and now, for all eternity, that you'll abandon science? If you do I won't have to kill you, Senku.
Flashback
"All right, next is Senku-kun. Seira-kun."
"I'm going to space." Elementary school Senku said.
"I'm going to be everything creative!" Elementary Seira said.
"An astronaut!" The teacher said looking at Senku.
"Ev-everything creative, Seira-kun. You need to choose one of those creative arts jobs" The teacher said.
"Why?" She asked.
"Because that's how it works" the teacher said.
"Why?" She asked.
"Because it's not possible to be more than one or two things." He said.
"Why?" She said. Realising he was getting nowhere he decided to let it be.
"Well, that's a great dream you two. Well, when you grow up..." the teacher said but was interrupted. By Senku. "No, we're doing it immediately."
"Then again we're just kids who dont know the first thing about science and everything."
" Yeah, but I really wanna do everything creative though and getting there could take some time.
"Why do you want to do everything creative Seira." Senku asked is little sister.
"So that we balance." She said.
"Balance?" He said confused.
"Yes. If your going to be an all science man then I'll be an all creative woman so that when we grow older we will dominate everything. Also knowing you you might mess up on some of your experiments so maybe I should also do science to help you out ever so often." Seira said.
Senku is surprised to see that his sister has put so much thought into this. He sister.
"Then let's go study every last thing." Senku said.
"Okay!" Seira said. The two walk together to the library. The two are found reading between mountains of books ranging form chemistry to history of art.
"We're going to try everything." Senku said as he was now taking apart his game in his room and his sister taking care plants while dancing outside.
A silhouette of a man can be seen looking out for the twins.
*In the car*
Seira is reading a cook book on Italian cuisines, while her brother is reading a book on Physics. (AN: nolabel on the book so I'm guessing)
"I can't help you. But Senku, Seira, If you're serious, you can accomplish anything through diligent application of science or diligent perseverance and hard work of the arts. I'm sure Santa Claus will give you two the tools you need."
One morning when Senku went to his room he found everything science related in his room. From canisters,a globe,a telescope and various other things that are still wrapped in boxes.
Seira walks in her room to find nothing in her room but a letter telling her to go to the backyard. When she got there, she was amazed. A workshop that covered about half of the backyard while the rest was covered in various plants and herbs that just made her eyes sparkle.
Inside the workshop she found all types of tools and a bookshelf packed with books about craftsmanship,designs and engineering.
She felt a tap on her shoulder and turned around to find the man there. He gave her a piece of paper containing a timetable for lessons such as dance, martial arts, music and painting. "Seira, the road you have chosen to walk is the hardest road I've ever seen but if going and you keep trying you will make it. Now Santa did all he can for you and Senku so the rest is up to you." He said.
"I understand. I will never give up and I promise that Senku and I will make you proud!" She said and the man smiled a pat her head.
"You can burn things with the point of light from a magnifying glass." Senku said.
"What an adorable experiment." The old man said.
At the dance hall. "1,2,3,4 Wow. Seira Seira you're amazing to see you improve in only a few days since you got here. Do you have any dance history?" Seira's ballet dance instructor asked.
"No, this is my first official lesson." Seira said.
"Eh?" The teacher said shocked.
At home. "Seira can I borrow you're frying pan? Senku asked. "Sure!" Seira said
The next day. "Sand iron and aluminium foil are awesome! The frying pan is melting from the thermite reaction." Senku said.
"Adorable...?" The old man said.
At cooking class. "Wow my little cheese cakes, your cakes look delicious. WOAH?!" He yelled in surprise seeing Seira's cake. A five layer red velvet cake with butter cream icing and candy roses covering the layers of the cake and chocolate sauce flowing from the top of the cake to the bottom like a waterfall.
"What do you think chef? Seira asked. The teacher said nothing out of shock.
At home. "Senku." Seira entered Senku's room with her melted frying pan. "I'm going going to kill you." She said.
"Kyaaa!!" Senku yelled. That night Senku experienced the wrath of ber sister for the first time.
Seira helped Senku his latest invention using some tools from her workshop.
"The liquid oxygen of the injector boils off 10 billion percent at a normal temperature, and it freezes when it's too cold. I'll have to keep trying with ethanol for a while until I switch to kerosene." Senku said. While young Taiju watched him. The old man is beyond speechless.
Bullies came to destroy the invention by stomping on it. Senku and Taiju try to stop them but Senku got blown away while Taiju is defending against the punches.
At the dojo. Seira stands in front Judo sensei asking for a fight.
"Don't be foolish girl you are still a white belt dont be overconfident." The sensei said.
"Its not a matter of over confidence I merely wish to know my level so I may not myself to improve." Seira said. The sensei could not refute her sound reasoning. "Very well,come at-" He couldn't finish his sentence as the little girl using his knees and waist jumped over him grabbed his arm and flipped him. The sensei was down and pinned down by the little girl. "So sensei, how'd I do?" She asked her sensei, unfortunately her couldn't reply due to shock. She was immediately transferred to a dojo of a higher level.
Years later in middle school. Seira and Taiju brought Yuzuriha to Senku. "Senku! You said you'd try it with light payload,right? We had Ogawa Yuzuriha-San of thr crafts club make us four passengers." Taiju said. Four tiny figurines of Senku,Seira,Taiju and Yuzuriha were presented.
"It's seriously embarrassing having a doll of myself." Yuzuriha said embarrassed.
"Really I think we all look cute though. You did a great job here Yuzuriha" Seira said, making Yuzuriha blush.
"What are you even using these for?" Yuzuriha asked.
The four went up the hill and Taiju was carrying the rocket. Senku is almost out of power but Seira came to the assist holding his hand to help him up the hill.
The four figures are put into the rocket. The teen kneel behind a Bush and Senku presses the launch button. The rocket ignites and takes off into the atmosphere but blew up.
"It blew up at a really high altitude." Senku said.
"Failed again?!" Taiju yelled in distress.
"Not entirely. " seira said.
Senku shows them the results and the four can be seen floating in space.
Flashback end.
"You can accomplish anything through diligent application of science." Senku said.
"Get away from him!" Seira yelled jumping in front of Senku protecting him. "You. Stay away from my brother." She said holding her daggers in her hands.
"Seira. I do not wish to harm you, but if I let your brother live, he would let civilisation develop." Tsukasa said.
"All the more reason to stop you from getting close to him. I can't let you kill the only family I have left! She said her eyes watering.
"Seira." Senku said putting his hand on her shoulder. "It's okay when he kills me he agreed to leave you alone."
"But there's no point if your dead. You promised. You promised we would be in this stone world together." She said as drops of tears fell from her eyes. Senku didn't say anything.
"Senku, I'd rather not kill you if I can help it." Tsukasa said.
"Bullshit! You can help it you just chose not to." Seira yelled angrily. Senku put a hand on her shoulder to somewhat calm her down.
"Senku I'll ask you again. Will you promise, me here and now, that you'll abandon science?" Tsukasa asked.
"I can't do that." Senku said.
"I thought you would be your answer." Tsukasa said.
"What are you blabbering about?" Senku said. "You were going to kill me at some point, no matter how I'd answered. To be on the safe side."
"Perhaps." Tsukasa said. Seira took this as her que to attack. She kicked in the direction of Tsukasa's face but he dodges. She keeps going on her flurry of attacks on Tsukasa. "Seira I don't wish nor want to harm you please stop." He punches but Seira dodges and they jump apart.
"I know Tsukasa. But I can't stop nor can I stand by knowing that you will kill my brother. Please just leave him alone." Seira said trying her best not cry. She's scared she doesn't want to lose her brother.
"Your love for your brother is admirable, but I can't do that." Tsukasa said and lept towards her closing the distance quickly and knocked Seira out with a hit on her temple. Tsukasa caught her in his arms before she could fall to the ground and laid her down gently. Coco came out and stood on her chest glaring at Tsukasa daring him to do more harm than he's already done to her.
Tsukasa walks back to Senku. Senku looks at his unconscious sister with melancholy.
"Do it one blow. Making me bleed out forever wouldn't be logical for either of us." Senku said.
"Dont worry. I'll bust your cervical nerve in a single blow. You'll be knocked unconscious, and then you'll die. I went make you suffer. I promise not to miss.
"Taiju- kun..." Yuzuriha said now sitting beside Seira.
"Yuzuriha, Senku!" Taiju said worried as he drops the sticks and rushes back to the hill.
" Senku, if we'd met 3'700 years ago... If we'd met before this planet became a stone world... You and your sister may have been my first friends." Tsukasa said.
"Maybe." Senku said.
Taiju is running up th hill trying to get to Yuzuriha, Seira and Senku. "Senku!" He yelled. But it's to late, Tsukasa already raised his arm, weapon in hand and strikes the back of Senku's neck.