Fourth season of Strike the Blood.

The village of Ootsuka—home to Shino Inuzuka, Sousuke Inukawa, and Hamaji—was lit on fire under the preconception that a virus had seen all of its life eradicated. Now surrounded by flames and on the verge of death, the three were approached by a strange man holding a sword. He tells them that they must reach a decision if they want to live. That night changed everything for these children. Five years later, the family of three now lives under the watchful eye of the small Imperial Church in a nearby village. All is fine and dandy until the Church attempts to reclaim the demonic sword of Murasame. To accomplish this, they kidnap Hamaji to lure Shino, now a bearer of Murasame's soul, and Sousuke, who possesses the ability to transform into a dog. The brothers must put their differences aside to rescue their beloved sister from the Church in the Imperial Capital, signalling the beginning of a very difficult journey.

While at school, Taniyama Mai and her friends like to exchange ghost stories. Apparently, there is an abandoned school building on their campus that is the center of many ghost stories. During the story, they are interrupted by a mysterious male figure. The person turns out to be Shibuya Kazuya, a 17-year-old who is president of the Shibuya Psychic Research Company. He was called by the principal to investigate the stories surrounding the abandoned school building. The next day, on the way to school, Mai passes the school building in question. While examining a strange camera she spotted inside, she gets surprised by Kazuya's assistant. Unknowingly interfering with the investigation, Mai breaks the camera and Kazuya's assistant gets injured. Kazuya forcefully hires Mai in order to pay for the camera and replace his injured assistant. From that point on, Mai begins to learn about the paranormal world and the profession of ghost hunting. [Written by MAL Rewrite]

Having completed their Stagiaire assignments, the residents of Polar Star Dormitory and their friends visit a hot springs inn. Though they planned on relaxing, these young chefs step up to the plate when the inn's entire kitchen staff suffer accidents. Unbeknownst to them, they will not be cooking for any ordinary patrons. Sometime after this trip, Souma Yukihira's desire for worthy opponents is stoked when he, Megumi Tadokoro, and the other Autumn Election quarter-finalists are invited to the annual Autumn Leaves Viewing event. The eight Tootsuki freshmen have a special opportunity to enjoy tea with the Elite Ten Council—including the Tenth Seat Erina Nakiri, who participates alongside her first-year classmates. Though it is framed as a friendly introduction between nine promising underclassmen and nine prestigious upperclassmen, Director Senzaemon Nakiri sees this meeting for what it is: a first encounter between the current reigning elite and their eventual usurpers. [Written by MAL Rewrite]