Pink de Ikou!

Synopsis

Ikumi is a schoolgirl who has a crush on Takase Hiroki, the most popular guy in school. However, Hiroki has refused the confessions of all the other girls, and it looks like he's spurned Ikumi, too! But it looks like luck is on her side, because with her little brother Haruka, she is living in Hiroki's house! (Source: StarryHeaven)