Back‑to‑school chaos erupts as Kaname Chidori and her war‑freak classmate Sousuke Sagara navigate new misadventures at Jindai High School. When Kaname lands in serious trouble, Sousuke adopts the persona of Bonta‑kun, the gun‑wielding, butt‑kicking mascot. While he struggles to maintain a normal teenage life, he must also protect his superior officer, Teletha Testarossa, who has left Mithril for a vacation and decides to spend a few weeks as a classmate of both him and Kaname.