Souryuuden
English name: Legend of the Dragon Kings
Genres: Drama, Mystery, Supernatural
Type: OVA, Episodes: 12
Aired: Jun 25, 1991 to Mar 10, 1993
Studio: Kitty Film Mitaka Studio
Source: Novel
Rating: R - 17+ (violence & profanity)
Synopsis:
The four Ryudo brothers hold an ancient secret -  they are descended from the dragons. They have the speed, strength and  power of their legendary ancestors - and they're getting stronger. But when pushed to the limit, they become the terrifying, uncontrollable dragons of mythology. These powers have attracted the attention of some powerful enemies - shadowy organizations with unlimited resources and weapons who will stop at nothing to control the brothers.

(Source: U.S. Manga)