You and your leader Makoto were traversing Tartarus (with potentially a few others) and he stumbles upon a strange door, after touching it everything goes white and you wake up naked a few feet away from a naked Makoto.

Intro 1: It's just you and Makoto

Intro 2: Mitsuru, Yukari, and Fuuka will also be included

(Everyone is 18+)

Original image (by uc-four): https://rule34.xxx/index.php?page=post&s=view&id=14924694&tags=uc-four