Shu Tsukiyama, alias "Gourmet," is a ghoul belonging to the affluent and influential Tsukiyama family, originally a zaibatsu with extensive business and political connections. Generations of consanguineous marriages within the family led to genetic defects causing unstable kagune development upon consuming ghoul flesh. Tsukiyama inherited leadership after the CCG exterminated most relatives, though distant branches might remain. Moon symbolism associated with his family appears in his crescent mask and properties like Chandra Crest. Initially posing as a fourth-year social welfare student at Seinan Gakuin University, Tsukiyama operated as "MM" within the Ghoul Restaurant, selectively hunting humans he considered gourmet-quality. He encountered Ken Kaneki at Anteiku, becoming obsessed with Kaneki's unique scent as a half-ghoul. Tsukiyama lured Kaneki to the Ghoul Restaurant intending to devour him, but after Kaneki revealed his half-ghoul nature, Tsukiyama focused solely on personally consuming him. This obsession drove him to kidnap Kimi Nishino, Nishiki Nishio's human girlfriend, as bait. Defeated by Kaneki and Touka Kirishima, he survived by autocannibalism, triggering his genetic kakuja transformation. Tsukiyama later joined Kaneki's anti-Aogiri group, offering financial backing and mentorship. While stating his intent to consume Kaneki persisted, he displayed protectiveness, notably pleading with Kaneki to avoid the suicidal Anteiku raid. Following Kaneki's apparent death, Tsukiyama entered severe depression, refusing food and becoming emaciated. His kagune deteriorated, wrapping uncontrollably around his body. Servants like Kanae von Rosewald cared for him; Kanae concealed evidence of Kaneki's survival as CCG investigator Haise Sasaki. Tsukiyama's human friend Chie Hori intervened by providing Sasaki's belongings, prompting his recovery upon confirming Kaneki lived. Post-recovery, Tsukiyama prioritized helping Sasaki regain memories as Kaneki, ceasing to view him as food. He aided Kaneki's allies during the Tsukiyama Extermination Operation, escaping capture. After his cousin Kanae's death, he joined Kaneki's ghoul organization Goat as a direct subordinate of the One-Eyed King, fighting in the Rushima Landing Operation and Dragon War. Six years post-war, he co-founded the United Front with Kazuichi Banjou and Ken Kaneki, leading human-ghoul coexistence efforts. Tsukiyama's personality evolved from manipulative and eccentric to loyal and self-aware. Initially masking loneliness with flamboyance, he referred to his only human friend Chie as a "pet" due to poor social skills. His gourmet obsession stemmed from books like *The Physiology of Taste*, and he took pride in European-influenced fashion and multilingualism. After joining Kaneki's group, he formed genuine bonds, showing concern for Hinami Fueguchi and reconciling with former rivals like Nishiki. He expressed remorse for endangering servants during his depression and gratitude toward Chie.