These are different stories involving Devilman's world. Some are about Devilman and add to the mythology some are separate stories that don't involve Devilman but take place the same time as the events in the original Devilman manga. They are illustrated by various artists. There are some color pages in the start middle and toward the end. There are some truly amazing art and stories in these volumes.
Number one is written and illustrated by Lazy Hagawari, Tatsuya Egawa, Katsuya Terada, Ken Ishikawa, Go Nagai and Shinichi Hiromoto.
Number two is written and illustrated by Hitoshi Iwaaki, Noriko Nagano, Go Nagai, Akihiko Takadera and Kazuko Yumeno.
Number three is written and illustrated by Noburu Miyama, Miki Toro, Shinobu Kaze, Sho-u Tajima, Masaomi Kanzaki, Yoshikazu Yasuhiko and Iou Kuroda.