[2] Written by Ikki Kajiwara and illustrated by Kentaro Nakajou, the manga was published in 1969 in the magazine Shōnen King.
[3] Ikki Kajiwara is known for his other sports manga, one of them, Ashita no Joe, is illustrated by Tetsuya Chiba and was published between 1968 and 1973 in Weekly Shōnen Magazine.
[4] The staff at Toei found it easier to animate Oni after gaining experience with physical contact sports anime Tiger Mask (also written by Kajiwara).
[5] The series chronicled the true story of kickboxer Tadashi Sawamura.
To which after some rigorous training, he learned a devastating finishing move: "The Jumping Vacuum Knee" (Shinku tobi hiza geri).