**—That summer, we found a “monster” with the face of a girl.** A secret between two boys, something they couldn't tell adults. To them, it was a creature of their imagination. Until that summer— Ken, cautious and timid, and Shun, bold and fearless. What the two boys found at the beach was a girl who was a “mermaid”, a being said to be “a dangerous presence” in their village. “Even if you see it, never go near it.” Will this encounter bring tragedy? Or— “You don't eat humans, do you…?”