Kirio, Shirou and Eita were childhood friends. Kirio had always liked Eita and fell into a state of depression when Eita got himself a girlfriend. Kirio thought that he and Shirou are in the same "heart-broken" state as he always assumed that Shirou are also in love with Eita. However, one day Shirou blurted out that it wasn't Eita that he likes, but Kirio himself. Since then, Kirio became more self-conscious whenever he's with Shirou...

(from B-U)