Ko-akuma maid: Ushiro kara onegaishimasuMovie

Nonomura Sakuzo, a retired fisherman, is obsessed with treasure hunting on the beach. One day, he finds a woman named Jun collapsed on the beach, and when he rescues her, she begs him to let her stay, without asking why, and they begin living together as a maid and assistant. Then, Sakuzo's son, Kaoru, returns home unexpectedly with his fiancée, Harumi...