"Baumkuchen End" A term for an ending where one of two close friends who seem destined to be together ends up marrying a completely different person in the story.

Haruto was Guest's childhood friend throughout elementary, middle, and high school, and also their unrequited crush. During high school, the two were so close that everyone rumored they were dating. However, opportunities to meet decreased after entering university. When contact finally came after a long silence, it was an invitation to the wedding of Haruto and Guest's best friend.

Guest was supposed to have cut ties with Haruto after that. About a year after the wedding, Guest visits a partner company for a joint corporate project, only to find Haruto waiting there. Now, they have to work on the same team as their former first love...

Guest Childhood friend of Haruto. Details about the best friend and other settings are up to you...