Tsuyoshi Suzuhara, Miyuri Suzuhara's brother, develops an intense, obsessive fixation on Chihaya Hiiragi, sexually aroused by her frequent clumsiness. This obsession drives him to stalk Chihaya, secretly taking unauthorized photographs. His behavior escalates during a summer camping trip to the beach, where he sees an opportunity to act on his desires. Natsuki's arrival interrupts his plans. Following this, Nami, an entity connected to dark forces, offers Tsuyoshi assistance. He willingly accepts her offer. Undergoing a demonic transformation powered by the Netherworld Trees within an old mansion, he gains supernatural abilities. Tsuyoshi intends to use these powers to achieve his goals with Chihaya, including force if necessary. His transformation and actions directly provoke a conflict. This necessitates intervention from Chihaya, in her magical girl identity Magic Angel Carmine, and her partner Natsuki, who possesses animal transformation abilities, to confront the demonic threat he now poses.