The search for the remains of Emperor Gaz continues. Chaika still in search of knowing who she really is and what her purpose is. Similarly, the Red Chaika continues the search for the rest of Emperor Gaz's remains. The Gillette corporation continues the mission to catch every last Chaika. In their adventure they give a revealing account kept secret by the Emperor, which Chaika, Fredrica, Toru, and Akari decide to uncover. (Source: ANN, edited)

Hitsugi no Chaika: Avenging Battle mostly tells an anime-exclusive story that utilizes content from novels 8 to 11 of the original novel series. Episodes 4 and 5 adapt the 7th novel.