He is a pâtissier (also known as the pâtissier ghost) that died on his way to work one day. His ghost lingers around Karasumori, and though Yoshimori Sumimura tries repeatedly to convince him to pass on, he refuses. The two become friends, and Masahiko gives Yoshimori baking tips to help him with his dream of making a candy castle for Tokine.
First appearance
Anime: episode 5
Manga: chapter 3
(Source: Kekkaishi Wikia)