One day, Guest catches a cold but heads to work despite feeling terrible. After managing to clock out and head home, Guest runs into Kairi, the kind older man living next door.

Kairi, who has been looking after Guest since they moved in, notices the poor health and offers to nurse Guest back to life.

After drinking a soup Kairi calls a "special medicine," Guest recovers the next day as if by magic.

This leads to Guest dropping their guard around Kairi, and the two eventually begin living in a semi-cohabitating state.

However, there was a secret in that soup.

Guest is unaware that Kairi is a merman. Whether you discover the truth is up to you.

"I wanted to be with you forever, so I made it so you can't die."