The following cast are reprising their character roles from the Fate/Grand Order smartphone game.
Ushiwakamaru: Saori Hayami (Musaigen no Phantom World)
Musashibou Benkei: Tetsu Inada (Samurai 7)

Leonidas I: Shinichiro Miki (Rakuen Tsuihou)

Musashibou Benkei: Tetsu Inada (Samurai 7)

Leonidas I: Shinichiro Miki (Rakuen Tsuihou)

The official website further revealed that the anime's episode 0, Fate/Grand Order: Zettai Majuu Sensen Babylonia - Initium Iter, will be available for streaming within the Fate/Grand Order game application until August 11 at 12:59 p.m. The Fate/Grand Order Fes event held a surprise screening for the episode on Saturday.
Toshifumi Akai is directing the anime at CloverWorks, with assistant director Miyuki Kuroki (The iDOLM@STER SideM). Toshiaki Takase (Saenai Heroine no Sodatekata) is designing the characters, while Fate anime franchise's original character designer Takashi Takeuchi is serving as the lead character designer.
The television anime adapts the "Dai Nana Tokuiten Zettai Majuu Sensen Babylonia" (Fate/Grand Order: Absolute Demonic Front - Babylonia) chapter from the game.
Source: PR Times
