Due to a mysterious disease, the genius Iria Akagami has been forced by her family to stay in a mansion on the isolated Wet Crow's Feather Island with only a handful of maids. To keep herself entertained, Iria invites a variety of fellow geniuses to stay as guests in her home, including computer savant Tomo Kunagisa and her unnamed assistant, skilled fortune-teller Maki Himena, famous artist Kanami Ibuki, academic scholar Akane Sonoyama, and renowned cook Yayoi Sashirono. These visits progress as normal until one of the guests is found gruesomely murdered in the night without a single clue as to the identity of the killer or a possible motive. Tensions rise between those on the island as the killer remains at large, and Tomo's assistant takes it upon himself to uncover the culprit's identity before the murderous events progress any further.

Time flies by; Hiroyuki and Akari are 12th-graders now. Both of them and their friends have grown up gradually in someway, physically or mentally, but one of their best friends is missing: the lifelike android Multi. To their surprise, Multi is brought to their campus again without notice, yet she is no longer the same Multi they have known.

Nora Handa is a boy who lives with Shachi Yuuri, who was adopted by his mother. With everyone supporting, the two of them grew up healthily even after their parents passed away. Shachi, who likes Nora the most, wakes him up every morning. Nora spends his happy student life with Michi Kuroki, who is a disciplinary committee, honor student at school and childhood friend of the main character, Yuuki Asuhara, who is a gal but is very bright and can talk his worries to, and more friends at school. One day, Nora meets a girl who calls herself Patricia at the park on the way to the school. Patricia is a queen at hell, and claims to come here to destroy the life on land. However, she is damaged heavily because she touched the life for the first time. The energy was stronger than her, so Nora needed to tend her. Patricia asked him to tell her about the mysteries of life, and he had to even explain the ero book that he found at the park...?!

From the light novel series written by Minase Hazuki, comes a story of love, action, and comedy. Yachi Haruaki is a high school boy who is naturally resistant to curses. After his father sends him a mysterious black cube, Haruaki awakes to find a nude girl named Fear standing in his kitchen. She’s the human form of the cursed black cube – and an instrument of torture! Utilizing her special abilities, Fear fights alongside Haruaki to defeat other cursed instruments and their owners.