Clavu, also known as Sous-chef, is a non-player character NPC within the Great Tomb of Nazarick. He is a myconid, a mushroom-person, and his head resembles the fungus Hydnellum peckii. Clavu works as the second in command of Nazarick's restaurant and normally operates in the Canteen. On a specific day each week, he manages a small bar located on the Ninth Floor that has only about eight seats. His regular customers in this bar are few and include the Floor Guardians Demiurge and Cocytus.

Proud of his profession, Clavu is most satisfied when working in his bar and prefers serving silent, elegant male guests. He gives careful consideration to his patrons, such as providing a straw to the penguin-like butler Eclair Ecleir Eicler so that he can drink in a dignified manner. Conversely, guests who lack proper etiquette will upset him. Like all inhabitants of Nazarick, Clavu is fiercely loyal to the Supreme Being Ainz Ooal Gown and the other forty-one beings who created them. While he generally dislikes outsiders entering the tomb, he is willing to cooperate with them if he sees potential advantages for Ainz and Nazarick.

Clavu’s role in the story primarily revolves around his duties as a cook and bartender. He is also seen working the land in a village area built on the Sixth Floor, tending a small field alongside dryads and treants. In this capacity, he raises a batch of mandrakes and teaches these semi-intelligent plants to praise Ainz’s name. He attended a private meal hosted by Shihouto where his signature cocktail, the Nazarick, was served. This drink is described as having ten beautiful colors in a single glass but no taste, a problem he is actively trying to fix. He was also charged by Sebas Tian to help prepare a banquet for visitors, providing the brand of alcohol for the event.

In terms of key relationships, Clavu is close friends with Eclair. Because they both work on the Ninth Floor, they see each other almost every day, and Eclair is allowed to call him by his nickname Piki. His relationship with Shalltear Bloodfallen is notably different. After Shalltear was freed from mind control, she was filled with self-pity and depression. Clavu initially invited her to his bar, but he soon found her behavior to be graceless and lacking in character compared to his preferred male patrons. Out of politeness to her status as a Floor Guardian, he remained outwardly respectful but was subtly rude, serving her cheap drinks like vodka with food coloring. Clavu showed some development in his duties, as he was involved in evaluating all outside food consumables after Nazarick's teleportation to the new world. His abilities are primarily in cooking and drink-making, as suggested by his title of Sous-chef. He also possesses some skill in gardening, as seen when he tends to crops and mandrakes. In the source material for the series, he is also noted as a manufacturer of potions, having thousands of healing potions in storage.