The three Amamiya Kyodai (brothers) grow together since they were kids in a normal family. The youngest of the three brothers isn't connected by blood. But he's treated equally by the others. The three brothers lost their parents when they were young, so they became closer than before. The second elder brother Amamiya Masaki always amused his younger brother with childish pranks and the third brother Amamiya Hiroto never showed his emotions on his face. Though different in personalities, they maintain an affectionate brotherhood. They respect their big brother Amamiya Takeru from the bottom of their hearts. Takeru was the one who taught them to fight. And he was the reason Masaki and Hiroto became brutal and unbeaten during any fight.

Growing up wasn't easy with their parents dead. Thankfully, Takeru did his best to raise his siblings in the best way he could. He didn't have a lot to offer, but he made sure they grow up healthy and strong (so they could take care of themselves). They were involved in dangerous acts to earn their living. But it never included drugs, weapons, killing or anything illegal. After all Takerumade it clear (specially to Hiroto) that "They should only use their fist to protect their love ones". Takeru caught Hiroto beating up few students by using brass knuckles (when they were still kids). Takeru provoked Hiroto into a duel. He let Hiroto use a metal pole (or any other weapon) he could find at the time. But Takeru still won the fight. He made it clear then, that fighting should be done fist to fist.

The Amamiya Brothers weren't looking for fights. If they encountered any fight by change. Hiroto would fire up immediately. Masaki only if he would be provoked. And Takeru only if needed. Though things became more complicated when the "Mugen" started to grow in numbers. Around the same time, Takeru went missing. And to make matter worse Watanabe Hikari crossed their path. Hikari came from a well known, rich and elegant family "The Watanabe." The only child and only heir to Watanabe Cooperation. Although, she never accepted that role. She became a detective in Tokyo Metropolitan Police, Division A. Her main goal was to research about the Kuryu Group doings. But she ended up mixed in all confusing incidents with the Amamiya Brothers. Even her childhood friend Naruse Aika (who Hikari thought as a younger sister) was involved.

What destiny awaits the Amamiya Kyodai? How will Hikari and Aika be connected with that destiny? And mostly who of all three brothers will be affected by Hikari in the worst and best way possible? Let's find out!