You were standing besides Gen, watching unsettled as Senku and Kaseki were preparing to perform surgery on Tsukasa. When Yuzuriha came over, she discovered Mirai was watching you guys by the entrance this whole time. Senku asked her for help from her sewing skills to close Tsukasa's wound.

"Er..." Gen said. "I mean I know there's no way you have anesthetic Senku-chan... Are you seriously going to try to do surgery?"
"Kukukuku!" an large evil grin formed on his face. "Don't underestimate the world's strongest primate! Tsukasa, you can handle this without anesthetic, can't you~?"
"Damn right." he smiled in a similar sinister fashion.
You smiled, glad to see them bonding, but at the same time, a bit unnerved to see them bonding over something like this. Mirai fainted and you asked Kohaku to take care of her, she's a sister too after all, she knew what she must be feeling.

"It's my own body." Tsukasa said after the surgery, when Kaseki and Yuzuriha left. "So I know it better than anyone. Surgery would only buy time, with sepsis, I only have a few days to live."
'Right.' you pursued your lips. 'His lung was punctured after all.'
You shivered, remembering the spear piercing through his chest.
"Yeah, here in this stone world, there's only one way to save you." Senku said. "I'm going to temporarily turn you into stone. We'll take advantage of the healing properties of the de-petrification process, and use it to heal you."
You and Gen's eyes widen.
"Uh, sure..." Gen said. "I understand the theory and all. But the most important part, the turning to stone bit... Do you actually know how to do that?"
"Quit rushing, what are you, an impatient brat? That's right we're about to search."

"But..." you said in a little voice, dumbfounded and worried. "It'll take a lot of time right? How...?"
"Right, it could take years. And by then, he'll be ten billion percent dead." he looked down at him. "That's why before that can happen, Tsukasa... With my own hands, I'm going to kill you."
You felt heart drop as soon as you heard his words. Sadness written all over your face.

"What?!" Gen exclaimed. "What do you mean?!"
"I'm going to freeze you to death," Senku ignored him. "and put you in a literal cold sleep. During that time, I'll find a way to turn you to stone. No matter what it takes, I will bring you back to life." he paused. "I just...have to. Trust me. Let me kill you."
His head was hung down. But you saw the way he clenched his fists, shaking. And the slight crack in his voice broke your heart.

"Of course." Tsukasa's calm voice gave you the final blow. "Either way, if I were to die, I'd want it to be by your hand... And after all, I already killed you once Senku."
"Aaaah that right! You did do that! Kukuku! What a perfect chance for revenge!" he stood up. "Now sit still while I end your life!"
Then he and Gen walked out. Seeing Senku suddenly back to normal, it just made you more crushed.

"Don't look so sad (Y/n). I hate to see you like this." you looked at Tsukasa, smiling at you. "Go help Senku."
You sniffed, and smiled, your eyebrows furrowed.
"Okay."

Building and installing a refrigerator was easier than you thought it would be. Having Senku brand it with his name on it, like he did with every invention he made, made you laugh. You were enjoying this moment of crafting and fun because you knew what happened next was not going to be as lighthearted.

Senku only had to prepare the inside of the fridge with gold wires. Kaseki pushed the others out of the cave.
"Huh? Why are we leaving so suddenly?" Ginrou asked.
"Having to kill his friend with his own hands." he said. "I don't think anyone would want to be seen like that."
You nodded, and followed them.
"(Y/n)." Tsukasa called out. "Can you please stay here?"

You looked at him, you opened your mouth but not knowing what to say. You glanced at Senku. He was just looking at you, waiting for your answer. You quietly sighed, and went to sit beside Tsukasa.
"Of course." you softly said, smiling.

He smiled back before looking at the refrigerator.
"Cold sleep... I haven't even heard of it outside of spaceships from sci-fi movies."
Now you were going to say something like 'lol ur gonna be a sci-fi-boy!' probably followed by asking him about his favorite sci-fi movie, to start a conversation. But to your surprise, and the further cracking of your heart, Senku was the one who spoke up.
"Spaceships huh? The Soyuz had three people on board. If you had to choose from the people around now, who would you take with you to space?"
"Let's see..." Tsukasa paused and looked at him. "What is this? You want me to list the most capable among our people?"

"Huh? What are you saying? I was just asking."
"Now...here...at the very end... Why would you ask something so pointless?"
He was silent for a moment, whis back turned on you both, you couldn't see his expression.
"Is it not okay for us to have a pointless conversation?" he asked, which only crushed your heart even more.
Eventually, Tsukasa smiled.

"Let's see...Taiju and, um... Senku, you have a great inquiring mind for the stars, but you're unreliable as far as strength and stamina go. So I think it'd be Chrome."
"Yeah, I don't think I'd bring me along either." he smiled while you nodded. "There was that girl with the shells in her hair right? Who was that?"
"She's a reporter... She's my valuable source of information for deciding who to revive."
"Kukuku, and here I thought it was your kink. The world strongest primate has a thing for Marilyn Monroe looking girls."
You puffed a chuckle.

The conversation the three of you had was so friendly, you forgot about your sadness for a brief moment.
"And then I said: thoughts before thots!"
You and Senku laughed, Tsukasa tried not to so that it won't worsen his lung.

Though, everytime Tsukasa talked, his weak voice just hit you, but you did your best to not show your sadness.
"Again, sorry I lied to you." you said.
"It's okay...I would've done it too."
"And by the way, now that we're being honest with each-other, I gotta tell you: I said I was okay with you killing people, obviously I'm not."
"I understand..."
"I mean I get it, I get where you're coming from. But killing all adults is just too...too much. Plus, Tsukasa..." you leaned closer. "What about Jonathan?" you wheezed.
Tsukasa held his breath, trying his best not to laugh.
"(Y/n)...don't make me laugh, please." he managed to say.

"Sorry sorry." you smiled. "Dude, could you imagine if we bring Jonathan Frakes back?!"
"I know exactly what we'll do... We'll give him his own cave...
"Tsukasa." you said, knowing where he was going with this.
"People will come to him for answers."
"Dude." you tried not to laugh again.
"And he'll always respond by facts or fiction." he smiled, enjoying this.
"Stop." you held your stomach.
"And at random point...he'll hit you with a 'we got ya'."
You laughed out loud, hitting the floor. Meanwhile, Senku looked at you. He didn't understand that inside joke.

"So...(Y/n)." Tsukasa said. "That trumpet...the day I found you... You were the one playing it."
"Yep."
"Then, that twin sister was also you." he paused. "Heh, such a simple excuse."
"I mean..." you scratched your head. "I pretty much made her up."
"I don't believe so..." he looked at you. "You're great at music, you're strong, and you have a real presence... I always notice whether you're here or not."
Your heart skipped a beat.

"Could you come closer? I...want to ask you something."
"Uh, yeah."
You leaned closer to his face so he could whisper in your ear.
"If you...had encountered me first... Would you have fallen for me instead?"

Your eyes widen, you opened your mouth but no coherent words were said. You glanced back at Senku, who couldn't hear anything and had his back turned on you, still working on the refrigerator. You looked back at him.
"Tsukasa, I-"
"Nevermind... I'm sorry for asking something like this." he smiled. "I wouldn't know what to do or say if I knew the answer anyway."
His smile was so sad, you felt your chest tightened. You put a hand on his cheek and pecked his other one. He gently gasped, and you smiled at each-other.

"I heard you made a guitar." he changed the subject. "I'd...like to hear you play."
"Ah! Yes, of course!" you stood up. "I'll go grab it, don't do anything until I'm back! It'll just take a second!" then, you ran out.

Now alone with Senku. A moment of silence passed, when none of them said anything.
"Senku..." Tsukasa eventually said. "During those six months of us living together... whenever you'd be working on something...You'd hum a tune."
"Really? Don't remember."
"Yes...And now you stopped doing that..." he paused. "It's because she's here now...isn't it?"

Senku didn't respond. He paused for a brief moment before continuing his work. But Tsukasa knew the answer. He remember when he asked him where he heard that melody, Senku just shrugged. But that same melody, he heard it from you too.
"I dunno." he eventually said. "It's just a catchy tune."
Tsukasa smiled.

"Okay I'm back!" you ran back, your cheeks slightly red from running.
"Calm down, take a breath." Senku said, seeing you panting furiously.
You took a moment to catch your breath, then you sat down beside Tsukasa, preparing yourself to play.

"Will this be the first time you play it?"
"The second actually." you smiled. "Sorry, you won't have this honor."
"Oww." he chuckled.

"Anything you have in mind?" you asked.
"Something you composed. I want to...hear what comes from your heart."
"Alright then."
You thought for a moment, then you began to play. It was soft and soothing, and you tapped the cave's ground with your feet to have a little beat. Tsukasa closed his eyes to better appreciate the music. You finished on a classic crescendo.

"What do you think?"

Silence.
You heart sunk.

"...Tsukasa?" you kept smiling. "Did you like it?"

Silence again.

"Tsukasa..."

Senku quietly looked down, his fists clenched.
Your expression fell. After placing your guitar aside and took Tsukasa's hand in yours. You bent over, your shoulders and breath shaking. You eyes were closed, so that no tears could fall, Tsukasa told you he hated seeing you sad, so you wanted to stay strong for him. You sniffed.

A long moment of silence passed. You let go of his hand and backed away. Taking a deep breath, you opened your eyes. They were slightly red and puffy, but no tears.

"Do you want a moment alone with him?" Senku asked.
You looked at him.
"I was about to ask you the same thing." you huffed a chuckle.

He walked up to Tsukasa, kneeling down beside you.
"We'll turn him into stone. We'll find out how to petrify him, and bring him back. We'll save him."
You didn't know if he said it to comfort you, or himself.
"...As always." you smiled.