Testarossa Stands Between the Demons and Ingrassia
The synopsis, published by Japanese entertainment news outlet Oricon News, sets up a full-scale crisis. Demon armies advancing from the north throw the western nations into chaos, and the forces close in on the Kingdom of Ingrassia. That is where Testarossa happens to be stationed, dispatched to the western nations' council on Rimuru's orders.
The episode's Japanese title is 「西方動乱」 (Seihō Dōran), roughly "Western Upheaval." The stills back up Oricon's headline, which promises a battle for Rimuru and a big gathering of characters: Rimuru appears mid-battle, and the lineup includes Diablo, the demon Rimuru summoned into his service, whose presence alone signals a serious fight.
Tensura numbers its episodes continuously across seasons, so Friday's broadcast counts as the 90th episode overall. It also ends a short pause in the schedule, arriving two weeks after the previous installment.
Where Season 4 Stands
Season 4 premiered on April 3, 2026, in Nippon TV's late-night Friday Anime Night block, airing on roughly 30 stations across Japan along with BS11, AT-X, and Animax. Eight Bit, the studio that has animated every season since the anime's 2018 debut, is handling a split five-cour run, with the first two cours airing back to back for a total of 24 episodes.
Miho Okasaki returns as Rimuru, and Takahiro Sakurai voices Diablo. The anime is credited to both Fuse's original light novels and Taiki Kawakami's manga adaptation, published by Kodansha.
Looking Ahead
Episode 90 airs late Friday night on August 14, 2026, in Japan. Internationally, Crunchyroll simulcasts Season 4, with new episodes landing Fridays at 7:00 a.m. PT in North America, Latin America, Europe, and most other regions.
Readers who want the source material in English are covered on both fronts. Yen Press publishes Fuse's light novels, which wrapped their run with volume 23 in November 2025, and Kodansha USA publishes Taiki Kawakami's manga.
Season 4 is planned as five cours in total. The current two-cour stretch covers 24 episodes, which leaves three more cours of Tensura still to come after this run concludes.