After finally completing the first route of his visual novel, Blessing Software's producer Tomoya Aki is optimistic about the future of his team and achieving their goal of creating the best game of the season. However, they still have a long way to go. For one, Megumi Katou still has an incredibly flat personality and is unable to fit the role of Tomoya's ideal heroine. The other members of Blessing Software, Eriri Spencer Sawamura, Utaha Kasumigaoka, and Michiru Hyoudou, often forget she is even there due to her lack of presence and character. Throughout the development of their game, Blessing Software learns the struggles of working in an industry where deadlines must be met and edits are made constantly, and the hardships of working in a group setting.

Hailing from America, Jabberwock—a street basketball team with skills comparable to those of the NBA—has come to Japan to play an exhibition match against Strky, a team of former third-year students who once played in the Interhigh and Winter Cup. However, due to the vast difference in skill, Jabberwock easily wins. Their captain, Nash Gold Jr., mocks the basketball style of all players in Japan by comparing them to monkeys. Infuriated by the nasty comment, Kagetora Aida challenges them to a revenge match. Because of pride and the belief that the results will be no different, Nash accepts the challenge. Kagetora then assembles Vorpal Swords, a team composed of the Generation of Miracles, including Kuroko Tetsuya and Kagami Taiga, for they are the only ones who stand a chance against a foe that seems unbeatable from every angle.

Alcia is a world governed by Count: numbers engraved on a person's body, representing any number related to their life. These Counts determine a person's social status and power in Alcia. If a Count reaches zero, the person is sent to the Abyss, a place rumored to be worse than death. Hina, a traveler whose Count is based on the distance she traveled, witnessed her mother get dragged down into the Abyss. Determined to fulfill her mother's last wishes, she sets off on a journey in search of the legendary Aces—heroes of the war that happened three hundred years ago, bearing a white star next to their Count. While wandering around, Hina encounters Licht Bach, a mysterious masked man with negative Count, and Nana, the owner of a tavern. In the midst of having a good time, Hina is tricked into a battle with a military soldier. However, despite his negative count, Licht rescues Hina and reveals that he has another count, one with a white star, one of a legendary Ace. Plunderer follows the journey of Hina and other inhabitants of Alcia as they discover the truth about their world, the Abyss, and the legendary Aces.

On his way to Areishia Spirit Academy, Kamito Kazehaya runs into a naked Claire Rouge, a student who had been bathing as part of a purification ceremony. She had been preparing to form a contract with a powerful spirit in order to acquire more power as an elementalist. Her efforts are wasted, however, when Kamito ends up with the spirit despite the fact that only shrine maidens can become elementalists. Yet to be discouraged, Claire then announces that Kamito must become her contracted spirit instead! After reaching the school grounds, Kamito escapes from Claire and meets Headmaster Greyworth Ciel Mais, who invites him to enroll at the academy. Although his life at Areishia will be far from easy as the only male student among the shrine princesses-in-training, he begrudgingly accepts in exchange for information about his former contracted spirit, Restia Ashdoll. Adding on to that, he also must fulfill Greyworth's main request: to win in the Blade Dance, a battle festival occurring in two months, where he will face the strongest elementalist rumored to be contracted with a darkness spirit.