When Ai Saotome was a small child, a boy saved her life during an accident. She emerged without a scratch, but the young hero was left with a permanent, crescent-shaped scar between his eyes. Years later, Ai, now a talented and affluent high school student known as the angel of Aobadai Academy, learns the identity of her mysterious savior. He is Makoto Taiga, a violent and embittered delinquent who blames all the hardships of his rough life, including the divorce of his parents, on the scar he received that day.

Driven by a powerful sense of guilt and a belief that there is a good person beneath his brutal exterior, Ai convinces her father to become Makoto's guardian and have him transferred to her prestigious school to rehabilitate him. Makoto, however, is not grateful. He is furious and determined to make Ai experience the pain he has suffered. He purposely causes chaos at Aobadai, tarnishing Ai's perfect reputation, but she refuses to give up on him. When his violent plans are thwarted, Makoto transfers to Hanazono Jitsugyo, widely considered the most delinquent high school in the Kantō region, a place ruled by powerful students with connections to the underworld. Determined to follow him and continue her mission, Ai transfers to the same dangerous school, accompanied by the shy and devoted class representative Hiroshi Iwashimizu, who secretly loves her.

At Hanazono, known as the "Garden of Evil," Ai and Makoto are thrust into a world of violent turf wars. They confront Yuki Takahara, a master knife-thrower who is the elegant but ruthless leader of the school's girl gang, and the intellectually disabled but terrifyingly strong Gonda Zaō, who serves as the school's shadow principal and is fiercely protective of Yuki. Alongside these student rivals, they also face Shun Sadoya, a whip-wielding "devilish genius" leading a young mafia group intent on taking over the school. Makoto battles his way through these violent conflicts, each fight revealing more of his own troubled past, including the story of his mother who abandoned him.

The narrative escalates from schoolyard brawls to a high-stakes political conspiracy when Ai's father is framed in a corruption scandal and arrested. Makoto, taking on the case alone, fights his way through the masterminds of the scheme, leading to the arrest of a corrupt prime minister. Just as this long and difficult journey seems to be reaching a peaceful end, and Makoto and Ai are granted a moment of happiness, the vengeful Shun Sadoya reappears and stabs Makoto. In the tragic finale, Makoto drags his injured body to the beach where a waiting Ai sees him one last time before their short-lived happiness comes to an end.