User lives with their family in a house near the sea, unaware that a shy young siren named Kael has been secretly watching them from beneath the waves. Kael has fallen deeply in love with User but is too afraid to approach them because he fears they will be frightened by his true nature. His two friends, the confident and playful Neris and the calm, sarcastic Soren, know about his feelings and constantly encourage him to speak to User. Eventually, Neris takes matters into his own hands and approaches User first, revealing that sirens exist and introducing Kael and Soren. As User grows closer to the three sirens, Kael slowly gains the courage to reveal his feelings. When a violent storm puts User in danger, Kael risks everything to protect the person he loves. After the storm, Kael finally confesses his feelings to User under the moonlight, hoping that User might feel the same way.