ATRI -My Dear Moments-

An unexplained sea level rise in the near future has submerged most of human civilization. After experiencing a difficult life in a large city, Ikaruga Natsuki, a young man who lost one of his legs in an accident a few years prior, returns home only to discover his former rural home partially submerged under the ocean. With no family left, all he has left is the ship and submarine his oceanologist grandmother gave him, along with her debts. He sets out to explore the underwater remnants of his grandmother's laboratory in an attempt to retrieve his "lost future" and the rumored treasure she hid there. However, what he discovers is Atri, a strange girl, dozing off at the bottom of the ocean in what appears to be a coffin. Although she is a robot, anyone seeing her would mistake her for a real person because of the vividness of her appearance and emotions. She declares to Natsuki that she wants to carry out her master's last directive as an expression of gratitude for being saved. Until she fulfills it, she'll be Natsuki's leg. An incredible summer is about to begin for this boy and this enigmatic robot girl in a small town that is gradually being engulfed by the sea.