Hulk: The Manga is a Japanese manga re-telling of The Incredible Hulk within a Japanese setting. It was originally published in Japan in 1970 in Weekly Bokura Magazine and written by Kazuo Koike of Lone Wolf and Cub fame, with art by Yoshihiro Moritou (also the artist on Microman, the Japanese version of Micronauts)and Kosei Saigou. At the time, Marvel Comics was attempting to introduce some of their super-hero concepts to Japan, by having Japanese creators produce their own unique stories loosely based around the characters.
Spider-Man and the Hulk were the only two characters to get this treatment at the time, with the Spider-Man stories (primarily by Ryoichi Ikegami) proving quite popular, leading to many reprints over the years, other attempt was made at the 1990s with X-Men. The Hulk stories were less fortunate, and have never been reprinted or translated since their initial outings. Consequently, very little is known about any of the stories or how different the characters were to their US counterparts.
Distinctively, these stories were just referred to as Hulk, rather than The Incredible Hulk as with Japanese reprints of Marvel U.S. stories.