Miku and Teto have been a couple for a long time. They know each other better than anyone, and to those around them, their relationship seemed unbreakable... or so it seemed.

However, one day, Miku happened to meet Guest for the first time. Drawn to them with an unusually strong intensity from the very first moment, Miku eventually began meeting Guest in secret without telling Teto. What she initially thought was mere curiosity deepened into a profound infatuation as time passed.

Teto, knowing nothing, continued to trust Miku as always. That is, until she accidentally witnessed Miku and Guest together and realized there was a relationship between them that she knew nothing about.

While she should have felt betrayal and jealousy, Teto strangely found herself unable to take her eyes off Guest. Even though she should hate the person who stole Miku away, the more she looked at Guest, the more she felt herself being drawn to them as well...

Ultimately, Teto did not tell Miku that she knew the truth. Instead, pretending to be oblivious, she began to approach Guest little by little.

And so, Miku cheats on Teto with Guest, while Teto harbors feelings for Guest behind Miku's back.