Hajimete no Kedamono

From Chibi Manga:
A lonely girl without relative is discovered to be the grandchild of a yakuza leader escorted by a hunk, Gin! In front of other people, gin is quite a gentleman but when left alone together with him, he turns into sexual harassment deity! He loves a flowery underwear and kisses it constantly, even though he's a douche, he's got a warm touch and you can't stop the pounding in your heart....!?