Eso is a Cursed Womb: Death Painting, one of nine such beings born over 150 years ago from a woman who could bear cursed spirit children. His creation resulted from experiments by the curse user Noritoshi Kamo, later revealed to be the ancient sorcerer Kenjaku, combining cursed spirits with humans. He and his brothers were eventually sealed as cursed objects within Tokyo Jujutsu High, stored alongside Sukuna's fingers. Standing 193 cm tall with a well-built physique, Eso has swept-back black hair (depicted as brown in the anime) and violet eyes with dark sclera. Thin eyebrows frame his face, each adorned with a stud piercing. His most distinctive feature is a large, bloody face embedded on his back, marked by sunken eyes, no nose, and a lipless mouth filled with sharp teeth. This causes him deep insecurity and intense rage if viewed. His revealing attire—a striped collar with a bow tie, white wrist cuffs, and a chest band connected via suspenders to combined thong-leggings—prevents the back face from becoming "stuffy." Eso's personality revolves entirely around his brothers, the older Choso and younger Kechizu. He believes the three are intrinsically connected, having existed in isolation for centuries with no bonds outside their sibling relationship. He exhibits eccentricity, enjoying playful banter and dramatic poses during confrontations. While not inherently hostile to jujutsu sorcerers, he prioritizes his brothers' safety and follows Choso's directives unquestioningly. His protective instincts are strongest for Kechizu, whom he shields in battle. Despite his outwardly welcoming demeanor, Eso harbors profound shame about the face on his back, reacting violently to anyone who sees it. Taken from Jujutsu High by the curse spirit Mahito during the Kyoto Goodwill Event, Eso was later incarnated into a physical body by Mahito in the Death Painting arc. He allied with Mahito's group, believing their goal of a curse-dominated world would benefit the Death Paintings. Tasked with retrieving a Sukuna finger, Eso and Kechizu confronted students Nobara Kugisaki and Yuji Itadori at Yasohachi Bridge. Eso initially offered Nobara a chance to flee, as killing sorcerers wasn't required. Hostilities erupted when Yuji and Kechizu emerged from a cursed spirit's domain. In the battle, Eso activated his Rot Technique, releasing airborne pathogens causing cellular decay. He later deployed his Maximum Technique: Wing King, generating massive crimson wings that fired blood projectiles. After Kechizu was wounded by Nobara's Resonance technique, Eso deactivated his Rot Technique per Choso's prior instructions. Yuji then severed Eso's arm with a Black Flash strike. Sensing Kechizu's death, Eso attempted escape by hijacking a car and taking a hostage. Nobara used Resonance on Eso's severed arm to inflict fatal damage, allowing Yuji to deliver the killing blow. Eso's final thoughts expressed regret for failing to protect Kechizu. A special grade cursed object, Eso possessed significant combat abilities. His primary Rot Technique involved manipulating his blood to release pathogens causing rapid cellular decay upon contact or inhalation; its potency increased via the Binding Vow: Revealing One's Hand when he explained its mechanics. His ultimate move, Maximum: Wing King, formed enormous blood wings for high-speed projectile attacks. He utilized Cursed Energy Reinforcement to augment durability, though this proved insufficient against Yuji's Black Flash. While stronger than Kechizu, he was notably less powerful than Choso.