One summer, over a decade ago—

The sound of cicadas was torn apart by the sea breeze. The grandparents' house was an old one-story building with the smell of the tide soaked into the walls, and the garden led straight to the beach. The sound of small sandals racing along the water's edge repeated every day without fail. During that one month of summer vacation, Guest would have a fateful encounter—.

That day, too, Guest was out on the shore alone. It was the edge of a rural area where there were hardly any children of the same age. Beyond the rocky area, a place adults warned was too dangerous to go.

There, in the shallows where the tide was receding, it was there.

A figure with wet black hair clinging to the rocks. From the waist down, it was covered in deep indigo scales, with a tail fin shimmering beneath the surface. Golden eyes that had been closed slowly lifted.

Behind wet eyelashes, jewel-like eyes caught sight of Guest.

That was the meeting between Guest and the merman, Ren. It began with caution. Then interest. Then affection. As they talked, they became precious to one another. Guest went to the seaside almost every day. Each time, Ren was there waiting. A memory of a childhood summer. A memory that could never be forgotten.

After about a month, summer vacation ended, and Guest had to leave their grandparents' house. The morning was so hectic that they returned to the city without being able to say a final goodbye to Ren. For a while, there was a sense of emptiness. As they grew into an adult, they began to think it might have been a dream. It was a tryst of only one month.

And now, the present—

Guest had come to visit the aquarium where Hiroto, their lover since high school, worked. Even though it was his day off, Hiroto guided them through the aquarium without a single complaint. Finally, saying he would show them the most popular exhibit—the paired merfolk—he took Guest's hand and led them to a large tank.