Kurōmaru Tokisaka is a member of the Tokisaka Clan, a group of Immortal Hunters of demi-human origin from the Yatagarasu tribe, trained in the Shinmei-ryū sword style. Transformed into an immortal through clan experiments meant to create a warrior capable of fighting other immortals, Kurōmaru was nonetheless resented by the clan for this immortal body, which they viewed as a curse. Banished from the clan, Kurōmaru was sent on a mission to kill Evangeline A.K. McDowell with orders not to return unless successful. Physiologically androgynous, Kurōmaru belongs to the Yatagarasu tribe, whose members are born without a biological sex and choose their gender at sixteen. For a significant time, Kurōmaru expressed a strong desire to be identified as male, often becoming annoyed when mistaken for a girl, a choice initially motivated by a wish to be a brother-in-arms to Tōta Konoe. However, as romantic feelings for Tōta developed, Kurōmaru's body began to naturally develop feminine characteristics, such as breast growth, even before turning sixteen—a biological response of their species where the body changes to become compatible with the gender of the person they love. Kurōmaru eventually accepted these feelings, confessed to Tōta, and fully transitioned into a woman, though retained a masculine name and often wore male attire. Kurōmaru is generally kind, easy-going, and capable of making friends quickly, having demonstrated loyalty to their clan despite poor treatment. After joining UQ Holder, they formed a very close bond with Tōta Konoe, viewing him as their closest friend and partner. They often experienced emotional hurt, such as when Tōta sought training from others, and struggled with internal conflict between the desire to remain a male comrade and their growing romantic feelings, which led to confusion about gender identity. Over time, Kurōmaru became more honest with these feelings and embraced a more feminine identity. A highly skilled swordsman in the Shinmei-ryū style with enhanced immortality regeneration, Kurōmaru's abilities grew significantly after training with Dana Ananga Jagannatha, to the point of being able to defeat a mature dragon—a feat normally requiring five Shinmei-ryū masters. During the physical transition to a female body, Kurōmaru experienced a temporary decrease in physical strength, ki control, and regeneration while adjusting to the new form. A significant power boost occurred after undergoing a ritual with the immortal hunters, becoming the living embodiment of the divine blade Hina-Mori, a spirit that had merged with them in childhood to save their life. This transformation granted Kurōmaru power on par with godlike immortals, including the ability to draw infinite magical power from the solar system. Key relationships include an older brother, Kiroumaru Tokisaka, the head of the Tokisaka Clan. They were close in youth, but Kiroumaru later acted cold and banished Kurōmaru to protect them from the clan and other hunters. The most significant relationship is with Tōta Konoe. After initially meeting as potential adversaries, they became close friends, with Kurōmaru developing romantic feelings for him. They formed a Pactio with Tōta, and their relationship deepened over time, culminating in a romantic and sexual relationship after a time skip. Within UQ Holder, Kurōmaru is member number 11 and part of a close-knit group with Karin Yuuki and Kirie Sakurame, who together form Tōta's primary romantic partners in a polyamorous relationship that endures for thousands of years. Kurōmaru's overarching narrative involves a journey of self-discovery from clan outcast to valued member of UQ Holder, heavily centered on exploring and deciding their gender identity influenced by love for Tōta. They participate in numerous missions and battles alongside UQ Holder, facing threats like the immortal hunter clan and the Lifemaker. Personal growth is marked by accepting their feelings and body, becoming one of the group's most powerful members, and committing to a lifelong relationship with Tōta and their partners.