Kurosaki Hisoka was born October 18, 1980, into the noble Kurosaki family near Kamakura, Japan. As the designated heir, he endured rigorous training in traditional Japanese martial arts: kendo, aikido, kyudo, and naginata. Severe familial abuse defined his childhood due to his innate empathic abilities, which allowed him to sense emotions, read thoughts, and perceive memories. His parents, Nagare and Rui Kurosaki, deemed these powers unnatural. They locked him in a cellar for extended periods, dehumanizing him as a "monster" to protect the family's reputation, fostering deep-seated trust issues and a profound fear of darkness.

At age 13, Hisoka witnessed Dr. Kazutaka Muraki murdering a woman under nearby cherry blossom trees. To prevent exposure, Muraki raped him and inflicted a slow-acting death curse, erasing Hisoka's memory of the event. The curse caused progressive deterioration—labored breathing, dropping body temperature, and chronic pain—over three years, resulting in his death at 16. Medical interventions failed, and his family concealed his condition. After death, he chose to become a shinigami (Guardian of Death) in the Ministry of Hades' Summons Division to uncover the truth behind his demise and pursue revenge against Muraki. The curse persisted in the afterlife, manifesting as red scars on his body during encounters with Muraki or in traumatic dreams, implying it would only lift upon Muraki's death.

Characterized by emotional reserve, bluntness, and a cold exterior stemming from trauma and empathic sensitivity, Hisoka finds crowds or strong emotions overwhelming, causing nausea, fainting, or physical pain, especially when touched. Despite this, he demonstrates keen detective skills and strategic subterfuge. His personality evolves through afterlife partnerships. He initially clashes with his assigned partner, Asato Tsuzuki, due to opposing temperaments—Tsuzuki's optimism contrasting with Hisoka's pragmatism. Shared experiences of isolation forge a profound bond. Hisoka repeatedly intervenes to prevent Tsuzuki's suicidal tendencies, offering declarations of undying loyalty, vowing to remain by his side "even if everyone else disappears." This relationship helps him gradually lower emotional barriers, though he retains a tsundere demeanor.

Hisoka's abilities center on empathy, extending to telepathy and psychometry (reading imprints from objects). Chief Konoe provided formal training in defensive magic and ofuda (paper charms). To augment combat prowess, he sought shikigami (summoned spirits), first bonding with Riko—a water-type, Spanish-speaking cactus who sacrificed himself to save Hisoka from Futsu (Kurikara's sword). Later, he pursued Kurikara-Ryūoh as a shikigami. His martial arts expertise remains intact, with archery as a noted proficiency. A historical curse upon the Kurosaki family—stemming from their ancestor Rei's killing of the god Yotonokami—condemned descendants to early deaths via accidents or illnesses, contextualizing Hisoka's abbreviated human life.

Hisoka's vendetta against Muraki drives his character arc, manifesting as obsessive rage during investigations involving the doctor. Muraki taunts him as "his doll," exploiting their history for psychological torment. Beyond this, Hisoka forms functional relationships with colleagues like Watari (bonding over intellectual pursuits) and Tatsumi (mutual respect for professionalism), though he avoids the playful advances of Saya and Yuma. His development underscores a struggle between vengeance and protective instincts, particularly toward Tsuzuki, reflecting his core need to prove self-worth after lifelong rejection.