This story takes place the first night on the ship back from getting the petrification device. Gen and Senku comfort each other.
After saying their goodbyes to Soyuz, Kirisame, and the rest of the villagers, Senku and the rest of the crew prepared to set sail back to Japan. By nightfall, Senku couldn't ignore the dull, throbbing pain in his left shoulder any longer.
'Ibara must have stabbed me deeper than expected,' he thought, 'Best to tend to the wound before it gets infected.'
Just as Senku was getting out the medical supplies, he heard a light tapping on the door to his sleeping quarters. (He was sharing this room with Gen and Chrome) Senku looked up to see Gen standing in the doorway, grinning.
"Hey, there, Senku-chan~," Gen called out in a singsong voice, "What'cha up to?"
"Nothing that concerns you, mentalist," Senku replied, distractedly.
At this point, Senku had already opened the medical kit and was starting to fiddle with the fastens on his clothes near his chest. Gen frowned slightly.
"Are you suuuure? Looks like you could use some help," Gen said as he casually walked into the room with his hands together in his usual pose.
Senku didn't even look up. "If you want to be useful, go get the hydrogen peroxide I have stored in the medical room," sighed Senku.
Gen thought and then responded, "I mean I can, but why aren't you in the medical room, then?"
"Too troublesome," Senku replied with a finger in his ear.
Gen chuckled lightly and left the room to get it for him.
Gen returned not too long after afterwards with the solution.
"Okay, Senku-chan~ I finally found it after reading EVERY bottle you ha-"
Gen's eyes widened as he looked up at Senku upon returning back to the room. Senku had fully removed the top part of his robe which was pushed down and resting on his waist. Senku was sitting on the cot next to the other bunkbeds looking intently at his wound under the glow from the crudely made lamp.
"Yea, thanks" Senku absentmindedly responded.
Without even looking up at Gen, he snatched the bottle and set it aside on the desk next to him as soon as he got close enough.
Gen blushed slightly at the sight of Senku's chest and stuttered slightly, "I-is there anything else you need help with?"
Senku, being a bit surprised with hearing Gen stutter, finally looked up at him. Gen looked back, silently praying that the room was dark enough that Senku wouldn't notice the pink in his cheeks. Senku glanced at the small wash bin on the floor next to the cot he was on and then back at his wound. Gen took this as a sign that he could at least help him clean his wound. Gen kneeled down on the floor next to the wash bin and took the cloth inside, rung out the water and took his first real look at the wound Senku had received on the island.