Lu Over the Wall

In the coastal village of Hinashi Town, stories about mermaids near Merfolk Island are treated as grim warnings—especially by Kai Ashimoto’s grandfather, who insists the creatures prey on humans. The Ashimoto household keeps music at arm’s length for similar reasons, leaving Kai to quietly channel his feelings into looped tracks he builds on his laptop and posts online.

Kai’s uploads catch the attention of upbeat classmates Kunio and Yuuho Ebina, who invite the withdrawn boy to join their rock band. Though reluctant, he agrees to accompany them to a practice session on Merfolk Island, where he encounters something beyond explanation. Later, while composing in his room, Kai draws the attention of Lu, a mermaid who responds joyfully to his stereo—revealing surprising abilities tied to music, including controlling water and forming legs when sound fills the air. As their friendship grows, Kai and Lu begin to open up, challenging the fear and boundaries that have long kept Hinashi Town from finding a more harmonious understanding.