Love Lesson

As a kid, Kousuke had spent a lot of time with his older, next door neighbor Minoru and even promised to marry him in the future. Now years later, Minoru continues to take care of Kousuke not just throughout the day, but also at night in the bedroom (even though the two aren't dating). But what will happen to their relationship after Kousuke catches Minoru in a heated argument with an unfamiliar man and Minoru wants to play it off like it's nothing?