Unlike many schools, attending Hyakkaou Private Academy prepares students for their time in the real world. Since many of the students are the children of the richest people in the world, the academy has its quirks that separate it from all the others. By day, it is a normal school, educating its pupils in history, languages, and the like. But at night, it turns into a gambling den, educating them in the art of dealing with money and manipulating people. Money is power; those who come out on top in the games stand at the top of the school. Yumeko Jabami, a seemingly naive and beautiful transfer student, is ready to try her hand at Hyakkaou's special curriculum. Unlike the rest, she doesn't play to win, but for the thrill of the gamble, and her borderline insane way of gambling might just bring too many new cards to the table.

In the year 2063, space travel is feasible and commercially available. As the cheerful Aries Spring arrives at the spaceport to attend a camp on the distant planet McPa, her purse is suddenly snatched by a reckless thief. Luckily, the athletic Kanata Hoshijima is able to retrieve it for her, and Aries soon discovers that he is among the group of teenagers who will be traveling with her on the excursion as team B-5. Upon arriving at their campsite, the group's trip takes a turn for the worse when a strange sphere of black light sucks them into the vast reaches of outer space. Stranded with seemingly no hope, they find an abandoned ship nearby that provides them with the means to return home. However, they soon discover that they are not as close to their campsite as they initially thought, but are in fact thousands of light-years away from home. With this realization, the nine members must cautiously manage their resources, maintain their strength, and unite as one to conquer the darkness of space together. While the reason behind their trip's sudden obstruction remains unknown, they nevertheless embark on the treacherous voyage back home aboard their new ship, the Astra.

A series of eerily similar suicides occupy newspaper headlines in late '90s Japan. Amidst all the bizarre resemblances, there is one detail that stands out above the rest: the victims have all taken their lives by leaping from the Fujou building, a run-down abandoned structure rising high above the city. Shiki Ryougi, a cold-hearted girl living in an empty apartment, suspects that these sinister events have a supernatural cause. Possessing a mystical power herself, Shiki works to investigate the incidents alongside Touko Aozaki, a doll-making detective specializing in magic, and her friend Mikiya Kokotou who works as Touko's assistant. Shiki unravels the mystery as she ventures through an enigmatic world to uncover the dark secrets surrounding the strange phenomenon.

In August of 1995, Mikiya Kokutou meets a young kimono-clad woman named Shiki Ryougi. When he finds out that they go to the same school, he attempts to befriend her. Though her upbringing is unconventional and she herself is strange, Mikiya is not deterred, and Shiki gradually opens up to him. But Mikiya's life will be changed forever by this simple meeting, and in ways that he never imagined, as he begins to see a deadly side to his new friend...