HAUNTED SAMURAI, a.k.a. SHINOBI DEMON: DUEL IN THE WIND, a.k.a. KAZE NO TENGU (1970), is an obscure samurai movie I uncharacteristically blind-bought from Diabolik DVD. It’s apparently never been on video and they made a limited edition blu-ray and I went for it.
Diabolik say it’s “based on the works of Goseki Kojima, the artist behind the legendary Lone Wolf and Cub.” Not the writer, Kazuo Koike, who was involved in quite a few movies, but the illustrator, Kojima. According to the film historian commentary track it’s based on a manga he wrote and illustrated, and it sounds like he calls it “Donenke” or something like that, but I could find no information about it anywhere. The opening credits do play over what looks like Kojima’s art.
(Update: It’s called Doninki [土忍記, “Earth Ninja Chronicles”] Thanks Matthew B.!)