[Kouji] Mesugaki ni natte Mesugaki ni Wakarasarechattara (Bessatsu Comic Unreal Mesugaki Wakaraserare Haiboku Shasei Vol. 2) [Black Grimoires]

A jobless loser who lurks outside a school becomes the plaything of two smirking brats determined to put him in his place—permanently. Transformed into a petite young girl and chained at their mercy, Yuichi Neyama learns the blackmail cuts both ways, and his only path forward runs through deepthroating, double penetration, and total surrender to a futanari duo that grinds his pride as a man into dust. What begins as mockery on the walk home ends in mind break, with the failed male remade as a blushing, broken cock sleeve living purely for their amusement.