Saiyaku ni Shite Madowazu

Masato works as a chef at a local restaurant. During one of his breaks, he had a chance encounter with one of his schoolmates, Mitsukuni, who accidentally spills coffee on his lap. In a rush, Mitsukuni immediately leaves, passively giving Masato a cleaning fee and an irritable temper. Worse, Masato's wallet gets in Mitsukuni's briefcase, which had all of his money and keys. As fate would have it, the two meet again later on at the restaurant Masato works at. While Masato perfectly remembers Mitsukuni during their high school days, Mitsukuni barely remembers the former. When Masato's home ends up catching fire, Mitsukuni is nagged by Masato's co-workers to take him in. Now that the two are living together, certain things come to light and unfold between them.

(Source: Fantasista Inc.)