Reiji Mitsurugi's legal path was forged in childhood. A classroom trial saw him defend classmate Ryuuichi Naruhodo against theft accusations, showcasing early analytical skill. This event cemented friendships with Naruhodo and Masashi Yahari, though Mitsurugi privately deduced Yahari as the true thief. His childhood took a traumatic turn during the DL-6 incident, where an elevator malfunction trapped him with his defense attorney father, Gregory, and bailiff Yanni Yogi. Amidst a struggle and oxygen deprivation, Mitsurugi inadvertently caused a gun discharge that killed his father, repressing the memory. The subsequent trial acquitted Yogi on temporary insanity grounds, fueling Mitsurugi's distrust of defense attorneys and spiritual mediums. His father's prosecutor rival, Manfred von Karma, adopted him, training him in ruthless tactics alongside von Karma's daughter Franziska; they formed a sibling-like bond despite their six-year age difference. Mitsurugi became a prosecutor at 20, rapidly earning a perfect conviction record and the "Demon Prosecutor" epithet due to aggressive tactics like witness coaching and evidence suppression. His debut case prosecuted Terry Fawles for murder against defense attorney Mia Fey, ending abruptly with Fawles' suicide – an event Mitsurugi later deemed his worst courtroom experience. Early career rumors implicated him in evidence tampering, particularly during the SL-9 incident convicting serial killer Joe Darke with flawed materials. He also prosecuted assassin Bodhidharma Kanis. His courtroom demeanor was often condescending, notably calling Fey a "novice bimbo." These victories drew intense scrutiny from media and the prosecutorial office regarding his methods. Consecutive courtroom defeats to Ryuuichi Naruhodo prompted a significant shift. Their first confrontation involved defending Mayoi Ayasato for murder, ending Mitsurugi's perfect record. A subsequent case against actor Will Powers saw him experience ethical conflict, ultimately assisting Naruhodo in exposing the true killer. This culminated in a personal crisis during his own murder trial, where Naruhodo defended him against Manfred von Karma. The proceedings uncovered von Karma's role in Gregory Mitsurugi's murder and Mitsurugi's repressed DL-6 trauma. Post-trial, rumors of his suicide spread after he vanished, leaving a note stating "Reiji Mitsurugi chooses death," though misinterpreted. He instead traveled internationally to redefine his prosecutorial philosophy, returning committed to uncovering truth over securing convictions. Mitsurugi's development included temporary defense attorney roles under extraordinary circumstances. When Naruhodo was hospitalized during a high-profile murder case, Mitsurugi assumed defense duties against Franziska von Karma, marking his sole playable appearance as a defense attorney within the main series. His investigative capabilities became central in spin-off titles where he solved interconnected murders. During these investigations, he confronted ethical dilemmas about his career path, torn between becoming a defense attorney like his father or reforming the prosecutor's office. He partnered with assistants like self-proclaimed "great thief" Kay Faraday and detective Keisuke Itonokogiri, forming effective partnerships despite initial reluctance. One investigation concluded with him temporarily surrendering his prosecutor's badge to address systemic corruption within the prosecutorial oversight committee. Later, Mitsurugi rose to Chief Prosecutor, focusing on institutional reform to prevent wrongful convictions. He prosecuted internationally across five countries and dismantled a transnational smuggling ring. Occasionally, he returned to the courtroom as a prosecutor, substituting for colleagues like Simon Blackquill and Nahyuta Sahdmadhi. His leadership retained characteristic rigor but showed increased willingness to collaborate with defense attorneys, including providing emergency transportation via chartered jet to support Naruhodo during time-sensitive cases. Mitsurugi's personality combines intellectual precision with social awkwardness, often perceived as aloof or condescending. He struggles with names, misidentifying cultural icons like "Mrs. Monkey" instead of "Mr. Monkey" and mispronouncing "Psyche-Locks" as "Psycholocks." A closeted fan of the Steel Samurai franchise, he concealed memorabilia in his office and law books. A deeply ingrained childhood habit of glaring to deter attention unintentionally intimidates associates. Though verbally dismissive of collaborators like Itonokogiri and Faraday, he relies on their assistance and expresses appreciation through actions rather than words. The anime adaptation softened certain interactions, omitting his threat to publicize a witness's suicide attempt and depicting explicit gratitude toward Mayoi Ayasato after courtroom assistance. Phobias stemming from the DL-6 incident include elevators and earthquakes. His backstory reveals academic excellence in golf, essay writing, and flute performance during school, though he rejected awards and public recognition. Emotional vulnerability surfaced in private failures, such as crying over origami difficulties before determinedly mastering the craft. His international prosecutorial work required confronting jurisdictional challenges and cultural differences in legal systems. Recurring difficulties involve eliciting straightforward name and occupation details from eccentric witnesses during courtroom examinations.