Mamoru Zaitsu

A cheerful boy who dreams of being a paramedic Ayumi falls for Mamoru quickly when he offers to take her to the nurse. Although he is in Ayumi039s class Ayumi only realizes that he is in fact Misao039s younger brother a day after she meets Misao. He is somewhat taken back by Ayumi he believes she is more fearsome than she may appear. Furthermore despite Ayumi039s feelings Mamoru has a crush on his next door neighbor Misaki Yamamoto. He later runs away with Kusuda and Sogabe after he was turned down by Misaki. Source: Wikipedia