Mugen

All five districts that form S.W.O.R.D were once one and at that time, the legendary group called Mugen is in full control of the whole area. This gang is created by childhood best friends Kohaku and Tatsuya. Their dream to ride together forever inspires them, hence, their group is named Mugen (infinity). Motorcycle enthusiasts Tsukumo, Ohta, and Konishi join them. Two young members, Cobra and Yamato, also join the group and Mugen starts with its seven original members.

As time goes by, the leaderless Mugen grows more influential and powerful. Their seven members quickly become ten, and then a hundred. However, Mugen begins to change. Some new members start to mess with drugs, blackmail people for money, and do all sorts of illegal things while bearing the Mugen sign and dragging Kohaku's name in it. When Kohaku realizes the situation, it's already too late.

The original members want to take different paths in life. Ohta and Konishi decide to become professional fighters abroad. The kind and amiable Tatsuya decides to open Itokan Diner and establish it as a place that Mugen members can call home. Kohaku is unhappy as he feels like he's slowly losing his friends. So, he declares himself the leader of Mugen despite the organization's current messy state. Soon, their so-called members run into some trouble with the Amamiya Brothers.

Tatsuya tries to stop Kohaku and ask him to start living a more peaceful life. Just when Kohaku is about to accept these changes, a traitor who has infiltrated Mugen causes an accident that leads to Tatsuya's death and sends Tsukumo in a coma. This leaves Kohaku in despair and Mugen disbands.