REMOW announced on Thursday that Satoshi Mizukami's Spirit Circle manga is receiving an 18-episode television anime that will air in Japan and stream globally in December 2026, per Anime News Network.

The announcement — ten years after the manga concluded in 2016, as IGN India notes — arrived with a teaser promotional video, teaser visual, main cast and staff.

The run length is unusually specific: Mizukami explained that adapting the seven-life story required a production length longer than one cour but shorter than two, IGN India reports. The manga ran in Shōnengahōsha's Young King OURs from May 2012 to 2016 and was collected in six volumes.

The striking development inside this announcement is the credit itself: the late Tatsuo Satō, who passed away in April according to Anime Trending, is credited as the anime's director and series composer — his final directorial work.

Anime News Network identifies the director of Martian Successor Nadesico, Stellvia and Atom The Beginning, and says Satō was also in charge of the series scripts, with production completed under the leadership of assistant director Kentaro Mizuno (Cardfight!!

Vanguard overDress, Wistoria: Wand and Sword) at studios NAGOMI and EOTA. IGN India reports that the studios and TWIN ENGINE issued a statement expressing gratitude for Satō's contribution and condolences following his passing.

The teaser promotional video doubles as a music reveal: Anime News Network reports it announces and previews the ending theme song "No Matter the World" (Koko ga Donna Sekai Demo), performed by Anna Nagase, with the song written specifically for the series.

That detail matters to fans because Nagase is also starring in the show as Kouko Ishigami, so the series' lead voice actor carries its closing music — a pairing the announcement itself engineered rather than a separate marketing drop.

The main cast, confirmed across the pack's reports, stars Kazuki Ura as Fuuta Okeya, Anna Nagase as Kouko Ishigami, Eri Yukimura as Rune, and Yūichi Nakamura as East.

As the outlets describe the premise, Fuuta is a middle schooler who can see spirits whose life upends when transfer student Kouko declares she will destroy his soul and break the cycle of reincarnation.

IGN India recounts that Fuuta uses the Spirit Circle device to revisit seven previous lifetimes across eras from ancient civilizations to the far future, with Satoru Fujimoto designing the characters and TWIN ENGINE producing.

The manga is available in English physically from Seven Seas Entertainment, and Crunchyroll began simultaneous publication in 2014, ANN notes.

The next checkpoint is the December 2026 broadcast and global streaming window itself, when viewers can finally judge how the completed production honors Satō's last vision.