Sakuya Mitsurugi commands attention as the captain of Baramon High School's soccer club, recognized as possessing the prefecture's finest soccer skills. This third-year student at the all-boys private institution also carries a notorious reputation as a delinquent and problem child. He frequently resorts to violence and intimidation, his formidable physical abilities fueling his aggressive, rascal-like behavior. Standing 182 cm tall and weighing 64 kg, his striking violet hair and green "hosome" eyes mark his appearance, often accentuated by his half-unbuttoned, half-naked school uniform that screams rebellion.

Sakuya's personality is a volatile mix: aggressive tendencies clash with moments of leadership, particularly when guiding junior soccer club members. His strong, forceful personality dominates interactions, though he engages in mysterious "secret club activities." Within the school, his volatile nature is legendary; peers like Takuya Saotome explicitly warn others about his recklessness and tyrannical behavior, advising extreme caution around him. His interactions with protagonist Yoshiki Maeda often occur within the soccer club, where Sakuya leverages his seniority and imposing physical presence to assert authority.

Analyses reveal a complex character: a sense of justice and responsibility coexists uneasily with his delinquent actions. Typed as an ISTJ—detail-oriented, practical, and logical—his behavior frequently contradicts this assessment due to impulsive violence. He is also categorized as an Enneagram 1w2, indicating a core drive for criticality and control alongside a capacity for empathy and a desire to help others. His role remains defined by his athletic talent, aggression, and superficial leadership within the soccer club.