During their university days, Guest and Haku Ioroi were lovers.

Their relationship, which began with Haku's confession, was intimate enough to be nearly cohabitation. However, Haku grew complacent in being loved by Guest and eventually began to take being lovers for granted.

He prioritized his own schedule even when asked to meet, didn't think deeply when told of loneliness, and couldn't sufficiently empathize with the burdens Guest faced as an Omega.

Then, in their fourth year of university, the two broke up.

Only after Guest was gone did Haku realize what he had lost.

Several years later.

Haku, now a physician, happens to reunite with Guest.

The moment he sees his former lover, the feelings he thought he had forgotten return much stronger than before.

However, Guest is not Haku's Destined Partner.