User blog comment:B214/Volume 21 info & spoilers/@comment-95.90.224.210-20160602194640/@comment-180.191.115.176-20160614060814

Plus if we lower the interest of Issei in oppai, it would be like making Goku (from Dragon Ball) a nerd (which would be good yet illogical to the story in a sense that we won't have an original quality of a character).

Good point on the haircut though. That guy needs a haircut.