Chapeau-jii is a demon character who appears in the Demon Prince Enma franchise. His very name reflects his nature, as jii is a Japanese suffix for an old man, and chapeau is the French word for hat. True to this, his physical form is that of a sentient, living hat. He is an extremely old demon, and his advanced age is a defining aspect of his character, particularly in the original video animation adaptation.

In terms of background, Chapeau-jii originates from the underworld and possesses encyclopedic knowledge regarding all matters of demons, the supernatural, and the realm of the dead. This expertise makes him a crucial source of information. His core role within the narrative is to serve as a guide and advisor to the main protagonist, the demon prince Enma. He is almost always seen perched atop Enma's head, a position that allows him to accompany the young demon on his missions in the human world.

The personality of Chapeau-jii is heavily influenced by his age. In the OVA, he is depicted as being in a perpetual state of drowsiness, frequently sleeping due to his old age. When he is awake, he acts as a calm and sagacious mentor. He is not a fighter and almost never takes direct action in conflicts. Instead, his function is to offer strategic counsel, explaining the best course of action for a given situation, and to use his supernatural senses to alert Enma to the presence of other demons. His motivations are tied to his duty; he is dedicated to assisting Enma in his quest to capture or eliminate demons that have escaped from hell into the human world, a mission typically carried out by a group known as the Demon Patrol.

Key relationships are central to his role. His most significant relationship is with Enma, who serves as his physical anchor and the primary agent who acts on his advice. He is generally portrayed as being loyal and supportive of the demon prince. He also associates with other members of the Demon Patrol, such as Yukihime and Kapaeru, though his interactions are primarily focused on guiding the team with his wisdom.

The character undergoes notable changes depending on the adaptation. In the OVA, he is a passive, often sleeping figure whose contribution is almost entirely intellectual. However, in the original manga source material, his depiction is quite different. There, he is portrayed as being younger and more vigorous. In this version, he has the ability to change his shape and appearance, possesses a more aggressive personality, and takes a much more active role in the action of the story, moving away from being a purely advisory figure.

Regarding his notable abilities, his primary power is his vast and deep knowledge of the demonic and magical world, which he uses to analyze threats and provide tactical advice. He also has the ability to levitate, allowing him to float and position himself. However, his direct combat capability is effectively nonexistent, reflected in his low danger level. In the OVA, his advanced age limits his physical activity almost entirely. In the manga, his powers are expanded to include shapeshifting. In some iterations, Chapeau-jii is also known for a verbal tic, habitually ending his sentences with the word jaja. Furthermore, the character is occasionally used for comic relief, sometimes being involved in risqué or voyeuristic gags. In spin-off series like Ghastly Prince Enma Burning Up, his hat form is capable of expressive facial changes for comedic effect.