Kazuki takes Toshiki to bed thoroughly, to reassure him and to work out his own understanding of what he is to Fuuga. Porn with Bondage, I-4

Toshiki liked being with Juubei, cherished the opportunity to feel wanted, needed. He liked it when Saizou was with them, because Saizou knew that sometimes you really did need to laugh, in bed. But sometimes it was good to belong only to Kazuki, for a while. That was how he thought of it, anyway.

He hadn’t realized that Kazuki knew that.