Archive of Our Own ^beta

“Senku, you can’t just stay huddled up in your lab the entire night! Not even Chrome’s in here at this hour!” Kohaku yelled from the doorway. Senku swiveled his chair to block her from view, lowering himself further into his blueprints.

“But he just made some interesting discoveries regarding the materials for the time machine. I’ll be fast, don’t worry, just go on ahead,” he pleaded. Kohaku crossed her arms. “Don’t make me tell Gen about this! I’m sure he’d have a field day giving you the rundown of all possible damage sleep deprivation could do to your brain.”

Senku sighed, knowing there was no chance they’d let him pull another all-nighter. Begrudgingly, he made his way over to Kohaku, wrapping an arm around her waist as he leaned his head against her side. “Can we sleep in the lab tonight?” he asked.

Kohaku glared at him. “We both know if I let you do that, you’ll just wait for me to fall asleep before returning to your notes.” She kissed him on the cheek before lifting him bridal style.

Ever since the Medusa problem had been resolved, Senku’s been more caught up in his science than ever. She could say the same for Chrome, given how those two seemed to live at the lab now. If ever she needed to find Senku, especially so late, it was no question where to check first.

“Y’know, the project is going pretty well so far,” Senku rested his head between Kohaku’s neck and shoulder as he spoke. She laughed, holding him closer. “I don’t know actually, I can’t seem to keep up with all your wild plans. I’d love to hear it in layman’s terms, though!” Kohaku grinned at the use of a new word Senku had taught her.

By the time Senku had finished a simplified summary of the time machine project details, they were at their front door. He insisted on living in the lab, but everyone was quick to disregard that, so instead they settled for a house only ten minutes away by foot.

Tsukasa opened the door, pulling them both into a hug. “Senku, it’s past midnight. You really shouldn’t be out this late, you didn’t even send a text.” Senku pouted, knowing he was in the wrong, but sat up firm in Kohaku’s arms, tilting his chin up. “Nowhere did I hear an ‘I love you’ or ‘I missed you.’”

Tsukasa let out a defeated laugh, pulling Senku out of Kohaku’s arms and into his own. “I love you, Senku. I missed you today at work.”

Gen finished tying his new silk robe, courtesy of Yuzuriha, as he walked into the hall. “You’re finally ack-bay, Senku-chan!” Tsukasa let Senku down so Gen could greet him with a hug and kiss. “Geez, you less than anyone should be this excited, you saw me just a few hours ago!” Senku pried himself from the mentalist. “I’m feeling a bit tired, so I think I’ll clock out for the night,” He said, before speed-walking down the hall to his room.

“Senku, we all agreed to sleep in my room tonight,” Tsukasa grabbed Senku by the wrist. “Plus, you haven’t even cleaned off yet. No way I’m letting you dirty any of our sheets that I so kindly washed this morning!” Gen huffed.

Senku attempted to free himself with no luck. “Yes, I’ll shower first, but I really think I could use some alone time tonight. Please?” Kohaku’s ears perked up. She might not have Ukyo’s refined hearing abilities, but she could recognize that manipulative tone anywhere.

“You want alone time? Senku I-can’t-sleep-without-holding-one-of-us Ishigami wants to sleep alone tonight? I say you just wanna hide away in your room, and stay up the rest of the night reorganizing your notes for the millionth time, but you weren’t gonna mention that part of alone time, were you?” Kohaku gently pinched his cheek, knowing she busted him.

Senku pressed his face against her palm, using his free hand to hold it there. “And here I thought I was the liar of the bunch. I nearly fell for that act!” Gen chuckled. He grabbed Kohaku and Tsukasa’s wrists, and with Tsukasa still holding onto Senku, led them to the bathroom.

“Maybe we should take a bath tonight, it’ll help us fall asleep,” Gen thought aloud, already turning on the hot water before anyone could object. “I sure know at least one of us could use the help,” Kohaku joked, intertwining her arm with Senku’s as he groaned. “I think we should just shower and go to sleep. The faster that happens, the faster I’m up for my 5 AM alarm and back to working.”

Gen clicked his teeth, shaking his pointer finger before tapping it on Senku’s chest. “You’re azy-cray if you think I’m letting you get up at 5 AM tomorrow with only 4 hours of sleep! You’re sleeping in, and I don’t want to hear any complaints, lest you want to let my whines ruin this delightful soak.”

Gen was already taking his clothes off, as was Kohaku. Tsukasa pulled open a drawer full of hair ties, putting Senku’s hair up into a bun. He parted his own hair into two sections and braided them, turning to Kohaku as he finished. “Need help with yours?” He asked. Kohaku shook her head. “Not with tying it, but you can help wash it if you’d like.”

Senku looked up at their skylight as he stepped into the tub, seeing how many constellations he could count from just this small view. Usually stargazing relaxed him, but he couldn’t seem to put his mind to rest, instead thinking about polishing his map to reflect the new positions of the stars after all these years. He made a crude one in the past, and did ask a group of revived astronomers to help out, but the impatience seemed to be catching up to him.

Kohaku noticed the crease between Senku’s brows from across the tub. She nudged Gen with her foot, pointing to Senku with her lips. Taking the hint, Gen grabbed Senku by the waist and pulled him onto his lap. “Would you like a massage, Senku-chan?” Gen whispered. Senku nodded, still looking up at the stars.

Gen started at Senku’s shoulders, treasuring each moan the scientist let out as he slowly added more pressure. Kohaku hummed from her side of the bath as Tsukasa rubbed circles onto her scalp. “You’re a dream, Tsukasa,” Kohaku leaned further into his touch. “You are too, dear Kohaku. My client over here won’t even say so much as thank you!” Gen feigned offense. Kohaku smirked, smelling an opportunity for banter. “So rude to expect thanks for a service you offered! I say you don’t leave a tip, Senku. And post a bad review.”

Gen gasped, pulling Senku to his chest. “Don’t let the lioness force you into such cruelty. You’d never be so rude to me, right, Senku-chan?” Gen pressed a kiss against Senku’s neck.

The massages continued silently until Gen finished. Senku went to move, but was held in place.

“And where is my tip, Senku-chan?” Gen held out his hand for Senku to kiss. Instead, Senku pointed down.

“Between your legs.”

Tsukasa and Kohaku suppressed giggles as Gen gasped. “You animal! I’m asking for a kiss!” Senku held Gen’s hand with both of his own, lightly kissing his knuckles. “I know, I know. Thank you, love.”

Tsukasa’s eyes darted to Senku’s, and he batted his eyelashes. “It’s been a while since you’ve used a pet name for me,” He said with what he felt was little implication. Senku knew the jealousy he’d long denied, though, and crawled over to Tsukasa’s side of the tub. “You’re amazing, too, dear,” Senku whispered, wrapping his arms around Tsukasa’s waist.

“No fair! I want somebody to cuddle with, too,” Gen crossed his arms, glaring at Tsukasa. Kohaku smiled fondly at Gen, crawling over and pulling him onto her lap. “No need to start a fight, I’ll hold you.”

Gen and Kohaku began to drift off, but Tsukasa could feel Senku’s grip tightening.

“You okay?” Tsukasa asked, playing with the loose strands that had fallen from Senku’s updo. He could feel Senku nod against him. “Just can’t seem to relax. Really wish I could have another hour with my notes,” Senku sighed. Tsukasa adjusted their positions, so that Senku was cradled in his lap. “That guilt trip won’t work on me, sorry. But I might know a way to help.” Senku pursed his lips, beckoning Tsukasa to continue.

“When’s the last time you touched yourself?” Tsukasa asked without expression. Senku’s face flushed, turning his face inwards to hide it from Tsukasa’s view. “When I was watching you and Gen.” Tsukasa trailed his nails up and down Senku’s side. “That was about a month ago. You should try indulging yourself more often, maybe you wouldn’t be so stressed.”

Senku rolled his eyes. “I’m not stressed, just can’t seem to sleep lately.”

“Because you’re stressed,” Gen quietly retorted, trying not to wake Kohaku.

Senku and Tsukasa turned their heads to Gen, not knowing he ever awoke. “Got up when I heard my name mentioned,” he shrugged, “so what are we doing tonight?”

“Each other,” Senku spoke.

“Have some class, Senku!” Gen sneered.

Tsukasa continued playing with Senku’s hair. “I was actually thinking we should focus on you, Senku. Are you alright with that?”

Senku hummed his agreement, trying to stand up, but being held down by Tsukasa. “We might as well stay here, instead of sweating and having to clean again, don’t you agree, Gen?” Gen gave a thumbs up as he gently shook Kohaku awake. “Kohaku dear, we’re having sex. Are you gonna join?” Kohaku stretched as she nodded her affirmation.

“What do you want, Senku?” Tsukasa asked. Senku spread his legs, still being held by Tsukasa. “Use your words, darling Senku,” Gen was beside the two men now, with a hand on Kohaku’s thigh.

“Please keep touching my hair, and I want you to touch me, Gen,” Senku looked down as he instructed, pulling on his own finger. Gen sat perpendicular from Tsukasa, between Senku’s legs. He took Senku’s dick into his hand, squeezing it lightly, slowly dragging his fingers down the length. “Kohaku, can I touch your breasts?” Senku asked, turning to where she sat, watching. She crawled closer, placing his hand on her chest. “You make it sound so formal.”

Senku bit his lip, trying to suppress his moans. Kohaku leaned over to kiss him, and pressed her hand against his throat, making him unable to keep quiet. “Senku-chan, you know how much we love to hear you, so please don’t feel embarrassed about it,” Gen picked up the pace of his jerking as he spoke.

Senku rubbed his head against Tsukasa’s chest. “Feels good,” he moaned, thrusting his hips into Gen’s hand. Gen firmly pushed him down, slowing his touch. “Let us handle it, dear. Just lay there and look pretty for me, hm?” Senku swallowed thickly at Gen’s command, turning his attention to Kohaku’s chest. “I wanna kiss you, come closer, please,” Senku stretched his neck, inviting Kohaku. She leaned in to bite his lip, and Gen whistled at the sight.

“Get a room, you two! I’ll almost get jealous that you’re able to devour each other whole, while I’m here with an empty mouth,” Gen joked. Senku raised his hips once more. “Help yourself.”

Tsukasa adjusted the two of them so that Senku’s waist was above the water. Senku’s dick twitched as Gen licked the slit, twirling his tongue around the tip and swallowing it in entirety. In the new position, Tsukasa was able to nip at Senku’s ear, earning him a choir of pleasure. Senku’s hand stayed on Kohaku’s chest, squeezing it every so often when he felt overstimulated.

Gen bobbed up and down, humming around Senku’s cock to let him feel the vibrations. “‘M close,” Senku panted, feeling his abdomen begin to warm. Tsukasa reached over and yanked Gen’s hair, pushing him down further on Senku’s length, speeding up his tempo. Gen moaned, feeling a buzz from the lack of oxygen he was able to get in. Kohaku continued to mark Senku’s neck, drawing him to his limit. She moved down to suck on a nipple, resulting in a sudden whine.

“Cumming, ‘m cumming,” Senku announced, unable to prevent himself from thrusting up deeper into Gen’s throat. His legs shook and wrapped around Gen as he kept releasing. Kohaku groaned at his nails digging into her chest, placing one of her hands over his to soften his grip.

Gen removed himself from between Senku’s legs once they went limp, opting to crawl to Kohaku’s side and take her free tit into his hands.

The four of them held each other for a couple minutes after Senku’s climax, with Tsukasa eventually leaving the tub to sit Senku on the toilet seat and wipe the cum off of his stomach, and dry him off. Senku slumped over, eyes fighting to stay open. “You’re hard, Tsukasa. Let me help,” Senku mumbled, reaching his hand out. Tsukasa massaged his palm, and kissed his wrist. “It’s alright, you need sleep.”

Kohaku finished drying Senku, grabbing a bottle of lotion to rub on both of them. She let down his hair and ran her hand through it to remove any knots. “Don’t take too long in ‘ere, boys,” she winked, carrying Senku out the bathroom to rest in Tsukasa’s bedroom.

Senku was gently placed onto Tsukasa’s king-sized bed, with a kiss to his forehead. Kohaku opened a few of Tsukasa’s drawers to find where he kept his underwear. The size would be a bit big for Senku, but at least he’d be covered. Plus, Tsukasa always loved seeing Senku in his clothes.

Kohaku curled beside Senku, still naked herself. She pulled the blanket over the two of them as she waited for the other two to finish. Soon enough, she couldn’t fight her heavy eyelids, drifting off atop Senku.

Tsukasa headed into his room while Gen finished his skincare routine in the bathroom, surprised to see Kohaku had already fallen back asleep. He slid under the covers to hold Senku’s free side. Tsukasa pet the back of the scientist’s head as he waited for Gen, soon greeted with the lights shutting off.

“Sorry I took a bit long, I decided to quickly wash my hair too.” Gen walked over to Tsukasa’s side of the bed and bent over for a kiss. “No room over here tonight, sorry. Kohaku must’ve been too tired to walk a few extra steps and put them in the correct spot,” Tsukasa said. Gen glared at him, pushing his shoulder. Tsukasa yawned. “Appears I’m too tired, too. Just cuddle with Kohaku,” Tsukasa whispered, holding Senku tighter. The moonlight highlighted the raised corners of his lips.

“No oblem-pray. She has better boobs than you, anyway,” Gen muttered.

“Love you too, Gen. Goodnight.”