Several months after Kunio defeated Sabu and rescued Hiroshi, brothers Ryuuichi and Ryuuji Hattori transfer to Reihou Academy. Within a few months, the brothers take control of the neighboring high schools using powerful fighting techniques, striking fear as the "Double Dragon Brothers". Riki, the banchou of Hanazono High School has no interest in the brothers or what they have been doing. But one day his girlfriend Mami goes missing and he receives a challenge from the academy. Enraged, Riki decides to make his way to the academy alone, but finds Kunio waiting for him outside his school. Kunio wants to help Riki rescue his girlfriend and he begrudgingly agrees.