Kimihiro Watanuki's life was never really normal. But in addition to his ability to see spirits, this sequel to xxxHOLiC finds him still slaving away for Yuuko, the bizarre owner of a strange shop, who promised to rid him of this ability. However, this otherworldly woman can only do so when he has worked enough to earn his wish. Such is the way for anyone who finds their way into the shop to have their request granted: a compensation equal to their wish must be paid. In this odd shop that straddles the world of the living and the dead, Watanuki finds himself doing household chores for the seemingly lazy Yuuko and her companions, while also helping out clients. Along with his classmates, supposed romantic rival Shizuka Doumeki and his crush Himawari Kunogi, Watanuki deals with the many misfortunes surrounding Yuuko's customers, as well as those that closely follow him and his friends.

In response to the worsening crime rate, Japan creates Tokyo Butei High, an elite academy where "Butei" or armed detectives hone their deadly skills in hopes of becoming mercenary-like agents of justice. One particular Butei is Kinji Tooyama, an anti-social and curt sophomore dropout who was once a student of the combat-centric Assault Division. Kinji now lives a life of leisure studying logistics in order to cover up his powerful but embarrassing special ability. However, his peaceful days soon come to an end when he becomes the target of the infamous "Butei Killer," and runs into an emotional hurricane and outspoken prodigy of the highest rank, Aria Holmes Kanzaki, who saves Kinji's life and demands that he become her partner after seeing what he is truly capable of.

Yura Yamato has just arrived at the high school division of Stella Women's Academy, when Sonora Kashima invites her to join a club called "C³". Sonora is the third-year student who became the new head of this club for military survival games. The other members include two second-year students (part-Japanese Karila Hatsuse and G36K-wielding Honoka Mutsu) and two other new students (Rento Kirishima whose family runs a Japanese sweets shop and the really short Yachiyo Hinata).

The idols of 765 Production continue on their neverending journey—towards a new stage, towards a bright and shiny future! The girls and their producer have gone through thick and thin, and have stood face to face with all kinds of difficulties. It's time again for the girls to foster their friendship, and through great discipline, they step forward to their starry future.