GeGeGe no Kitaro: The Demon Flute Elohim Essaim (1985)

One day, Kitaro received a letter from a postman in the spirit world. The sender was Kitaro's best friend, Akuma-kun. According to the letter, she wants you to help her beloved homeroom teacher Hoshi-sensei, who has gone missing. It is said that late at night for two months, Hoshi-sensei fell in love with Sakurako, the spirit of cherry blossoms. Kitaro and his friends find out that the teacher is in the ruins and go to help him.