Warner Bros. released the film digitally last April, and on Blu-ray Disc Steelbook, DVD, and Blu-ray/DVD combo pack last May. The release included the Japanese audio track as well as the English dub. The anime debuted in Japanese theaters last June with the Japanese voice cast.
Junpei Mizusaki, the producer of the opening animation sequences for JoJo's Bizarre Adventure and JoJo's Bizarre Adventure: Stardust Crusaders and Kamikaze Douga CEO/founder, was the film's director. Kazuki Nakashima, who was in charge of the series scripts for Gurren Lagann and Kill la Kill, was the screenwriter. Takashi Okazaki, the creator of the Afro Samurai manga, was the character designer for the film. The project also involved English-language screenwriters Leo Chu and Eric Garcia, the executive producers for the Afro Samurai series and Afro Samurai: Resurrection film.
Kamikaze Douga worked on the project, and Yuugo Kanno (Psycho-Pass, JoJo's Bizarre Adventure: Diamond Is Unbreakable, Ajin) composed the music. The anime's website stated the project was three years in the making.
Source: Batman Ninja manga volume 1