Kowamote Koukousei to Jimiko-san

Synopsis

"I've come to get you." Reuniting with the pretty boy who moved away 10 years ago... who came back with an ultra scary face?! Suddenly appearing before, Sachi (26 years old), the manager of a small flower shop, is a high schooler with ultra terrifying looks, telling her that he has come to meet her as promised as he draws closer... (Source: MangaUpdates)