DNA² ~Dokoka de Nakushita Aitsu no Aitsu~

Junta has a problem: he's deathly allergic to girls! All this changes with the arrival of Karin,​ a gorgeous time-traveler who transforms him into the Mega-Playboy,​ the sauciest girl-magnet around.​ Suddenly,​ Junta's wildest dreams have come true,​ and all the prettiest girls in school have fallen in love with him.​ With so many adoring fans,​ mayhem is sure to follow,​ and Junta finds himself in the center of one hilarious romantic mishap after another.​

(Source: Discotek)