He is Ren's manager. When first seen he is a serious character, later on he is used largely for comic relief. We get a better understanding of Ren’s subtle emotional shifts from Yashiro’s not-so-subtle reactions to Ren’s interactions with Kyoko. He fully supports a romantic relationship between the two and often needles Ren about his lack of progress in that area. He also tends to associate anything Ren says in relation to Kyoko and his feelings for her, even before Ren himself came to terms with them.
He must use latex gloves when handling electronics because any electronic device that he touches directly will soon be rendered useless. In particular, he has mentioned that a cell phone will die after about 10 seconds of direct exposure to his skin.