DASS-434 Eng Sub. What if I had a casual relationship with the girl next door for three days while my girlfriend was on a trip? Mary Tachibana.

The story follows Hajime, who discovers his girlfriend has been unfaithful with a friend. Devastated and alone, he catches the attention of his next-door neighbor, Mary—a beautiful novelist. Sensing his pain, she offers comfort, leading to an intimate encounter. Over the three days his girlfriend is away (on what turns out to be an affair-related trip), Hajime and Mary grow remarkably close. They share passionate moments, deep conversations, and lover-like intimacy, blurring the lines between neighbors and something more.

Yet, a simple door separates their apartments, symbolizing the thin barrier between their current lives and what could have been. The narrative ponders endless “what if” scenarios—countless parallel worlds, each shaped by different choices in love and partners. This marks the beginning of a multiverse-style series featuring Mary Tachibana, blending emotional depth with steamy scenes.