If we look back at chapter 2, Fukami said right away that he's a bottom, so even though at that time he never had that experience, he felt comfortable enough with Kaji to open up about that :> Sweet.
If we look back at chapter 2, Fukami said right away that he's a bottom, so even though at that time he never had that experience, he felt comfortable enough with Kaji to open up about that :> Sweet.