To LOVE-Ru OVA

Synopsis

As Saruyama tries to explain about boobs to Rito, the girls including Lala overhear the conversation. Lala asks for more facts about boobs and gets the idea that all men are interested in breasts. She makes an invention that will make her boobs the perfect size, but Rito flies out from a school window and crashes into the invention, turning him into a girl. After Lala and Mikan tease him with girl clothing, Rito runs out of the house. He gets bombarded by many men including Saruyama and the principal. Saki finds Rito (still as a girl) unconscious and brings him/her into Saki's mansion. Riko (Rito as a girl) begins to feel that being a girl may be better than being a boy. He/she gets turned back into boy by one of Lala's invention when she appears out of nowhere, and the episode ends when Saki delivers a painful beating upon Rito by punching him in the face with a baseball bat.

(Source: Wikipedia)