The VENUS Program is an idol scoring system that is entirely impartial, using AI and data to rank candidates based on an array of factors. To determine the rising stars of the idol industry, the annual VENUS Grand Prix is held utilizing these algorithms. Among all the idols that have participated, none have been as outstanding as Mana Nagase. However, on the day of the tournament's finals, a tragic accident suddenly ends her career. Kouhei Makino, who previously worked as Mana's manager, continues his career at Hoshimi Productions years after her death. Wanting to build a new team of idols, he accepts interviews from various girls. Unexpectedly, one of the interviewees is Kotono Nagase, Mana's younger sister, who is striving to carry on her sister's legacy under the tutelage of her former advisor. Also auditioning is Sakura Kawasaki, whose voice sounds astoundingly similar to that of Mana. Both Kotono and Sakura pass the evaluations, joining a group of eight other aspiring young girls. Living in a shared dormitory, the 10 members work together to learn more about what it means to harmonize as a team. United by an ambitious endeavor, the girls compete their way to the top as they traverse through the unforgiving world of idols.

On a remote island far from the mainland named Urashima, a man washes ashore, with no recollection of his name or homeland. What he does recall, however, is that he is a time traveler with a mission: to save a certain girl from harm. As nightfall arrives, he meets Rinne Ohara, a girl who sings a tune that reminds him of a specific name—Setsuna—and decides to use it as his own. Knowing another "Setsuna" herself, Rinne takes him to her household as a servant, hoping that he is the same one she remembers. On the other hand, Setsuna continues to learn more about Urashima, desiring to identify his lost past. He comes to know about the island's folklore, its three great families, and the endemic disease that prevents anyone afflicted from stepping out into the daylight. As the mysteries of his missing memories and Urashima itself unfold, Setsuna must remember his purpose and fulfill his mission as soon as possible. But, as he witnesses the myriad of troubles plaguing the island, Setsuna begins to question—is his temporal displacement merely an effort to change a single girl's fate?

Poor Shinichirou Asano has the worst of luck. His parents abandoned him and ran off to Europe. If that isn't bad enough on its own, they barely left him any money to take care of himself. In order to pay rent and keep a roof over his head, he has to work. Unfortunately, he was just fired from his last job and as a high school student, he doesn't have many other prospects. One evening, he's attacked by a centipede monster on his way home. Shinichirou is saved by a mysterious girl with a bow and arrow, who he later discovers is Sakuya Shimazu, a beautiful student who attends his school. But when he later helps an injured girl, he discovers two things. First, the injured girl isn't human at all but rather a nekomata, a two-tailed demon cat. And second, Sakuya comes from a family of exorcists, who've protected humanity from rogue monsters and spirits for generations. Because Shinichirou was responsible for releasing the nekomata, Sakuya enlists his help in recapturing the demon, but that's just the beginning of Shinichirou's relationship with Sakuya. It turns out the Shimazu family needs a housekeeper and it just so happens that Shinichirou excels at cooking and likes to clean! It may not be his dream job, but if it pays the rent and puts food on the table...

Shinichirou Asano, Sakuya Shimazu, and their friends arrive at one of the Shimazu family's private islands for a vacation. However, what starts as a fun and relaxing outing soon takes a turn for the supernatural when the group heads into the island's forest. As their companions mysteriously vanish one after the other, Shinichirou and Sakuya quickly find themselves all alone on a seemingly uninhabited island.