Shū Tsukiyama, alias "Gourmet," belongs to the wealthy and influential Tsukiyama family, led by his father Mirumo Tsukiyama. He studied Social Welfare at Seinan Gakuin University's Department of Human Sciences. As a ghoul operating in Tokyo's 20th Ward, he gained notoriety for selectively hunting humans and refining his culinary preferences, including stalking victims like Misono Karube to harvest specific body parts such as her eyes. His family's conglomerate, the Tsukiyama Group, held significant influence across multiple industries, enabling their discreet existence. Tsukiyama was affiliated with the Ghoul Restaurant under the moniker "MM," though he later betrayed the organization. Tsukiyama presented a cultured intellectual persona with refined European tastes, often incorporating French, Italian, or English phrases into his speech, masking a predatory and narcissistic nature driven by an obsession with novel sensory experiences. His encounter with Ken Kaneki at Anteiku café sparked an intense fixation due to Kaneki's unique scent as a half-human, half-ghoul hybrid. Tsukiyama lured Kaneki to the Ghoul Restaurant intending to devour him, kidnapping Kimi Nishino to manipulate Kaneki. After Kaneki defeated him during a confrontation at a church, Tsukiyama sustained severe injuries but recovered by consuming his own flesh. Following his defeat, Tsukiyama joined Kaneki's group under the pretense of mentorship while secretly plotting to eat him. He provided financial support and tactical aid during missions, such as the rescue operation at Aogiri Tree's hideout where he fought alongside Uta and Yomo against Noro. Despite initial selfish motives, Tsukiyama gradually developed genuine loyalty to Kaneki, tearfully pleading with him to avoid suicidal actions during the Anteiku Raid. When Kaneki seemingly died and resurfaced later as the amnesiac CCG investigator Haise Sasaki, Tsukiyama spiraled into deep depression. He neglected self-care, leading to emaciation, loss of kagune control, and violent outbursts, requiring constant supervision by family servants like Kanae von Rosewald. This deterioration persisted for two years until learning of Kaneki's survival revitalized him; he immediately sought out Sasaki, disregarding his frail health. During the Rosewald Extermination Operation, Tsukiyama faced CCG persecution but regained his resolve to protect his family and allies. After Kanae's death, he committed fully to Kaneki's cause, joining the ghoul organization Goat as a direct subordinate of the One-Eyed King. He participated in critical conflicts like the Rushima Landing Operation and the Clown Siege, collaborating with figures like Nishiki Nishio and Hinami Fueguchi. His leadership skills led him to co-found the United Front with Kazuichi Banjou and Kaneki, advocating for human-ghoul coexistence. Later, he aligned with the TSC (Tokyo Security Council) as a Peacekeeper. Tsukiyama's relationships reflect his evolution: his bond with Kaneki shifted from predatory obsession to selfless devotion. He maintained a decades-long friendship with the human Chie Hori, whom he termed his "pet" due to her immunity to his manipulations and willingness to aid him despite his ghoul nature. He shared a complex dynamic with Kanae von Rosewald, a devoted servant who viewed him as family; Tsukiyama expressed remorse for the suffering his depression caused Kanae. His interactions with other ghouls like Touka Kirishima and Hinami Fueguchi evolved from transactional or antagonistic to mutually respectful alliances. Physically, Tsukiyama appeared as a tall, well-groomed young man with blue hair, often dressed in flamboyant European-style suits. During his depressive period, he became emaciated with unkempt hair and nails, wearing only a plain robe. His kagune, classified as koukaku-type, could manifest as protective armor or bladed appendages. Post-recovery, he regained his former appearance but adopted more subdued attire during missions.