Born in January 1988, Doumyouji Tsukasa is the heir to the immensely wealthy Domyoji Group conglomerate. His parents resided primarily in New York for business, leaving him emotionally neglected and raised by household staff, notably the maid Tama. This upbringing fostered deep-seated feelings of abandonment, exemplified when he questioned Tama about his parents' lack of care. His older sister Tsubaki provided occasional guidance, physically disciplining him yet also showing care through gestures like learning to cook his favorite food. Tsukasa's childhood friendships with Rui Hanazawa, Akira Mimasaka, and Sojiro Nishikado began in kindergarten at Eitoku Academy, later forming the F4 group with Shizuka Todo. During elementary and middle school, Tsukasa exhibited increasingly violent behavior, regularly engaging in physical altercations that resulted in severe injuries to others. His family routinely used their wealth to conceal these incidents, including one case where a victim suffered ruptured intestines. He developed a pattern of rejecting emotional intimacy, briefly experimenting with casual encounters before finding them meaningless. A kidnapping attempt during this period further reinforced his aggressive self-defense mechanisms. Upon entering Eitoku High School, Tsukasa solidified his role as F4 leader, leveraging familial influence to dominate the student body. The group implemented a "red card" system targeting students who defied them, leading to systematic bullying campaigns that often forced victims to withdraw. His worldview centered on the belief that wealth and status could resolve any conflict, demonstrated when he dismissed apologies as insufficient without material consequences. Tsukasa's life transformed upon encountering Tsukushi Makino, a middle-class student who defended her friend after an accidental collision. Her resistance—culminating in her punching him and declaring war on F4—captivated him. His initial attempts to control her included kidnapping her for a makeover and offering luxury in exchange for submission, which she rejected by asserting her self-worth beyond material possessions. This defiance challenged his core beliefs about power and value. His fixation evolved into genuine affection, marked by protective declarations like "the only one allowed to bully this girl is me" when intervening against other bullies. Key moments accelerated their relationship: an accidental kiss during a blackout at a party, a fever-induced overnight confinement in an elevator where she cared for him, and his life-threatening confession when he allowed himself to be beaten by thugs to protect her. Tsukushi's influence gradually softened his aggression, evidenced when he spent hours straightening his hair after she criticized it. Tsukasa's romantic pursuit faced significant obstacles, including Tsukushi's initial feelings for Rui, leading to violent conflicts that temporarily fractured F4. His mother Kaede actively opposed the relationship, employing financial pressure and manipulation to separate them, including bribes to Tsukushi's family and forcing Tsukasa's relocation to New York. The Teen of Japan contest became a pivotal battleground, where Tsukasa secretly bargained with his mother: if Tsukushi lost, he would study abroad in exchange for her family's safety. Despite her loss, Tsukushi intercepted his departure at the airport, confessing her love and prompting him to stay. His character development revealed underlying vulnerabilities beneath his abrasive exterior, including loyalty to F4 and eventual recognition of his own emotional limitations. Tsukasa's journey concluded with a hard-won relationship with Tsukushi, overcoming class barriers and familial opposition through mutual persistence.