Belmondo (Berumondo in Finnish version) is a wolf ganin working under the Gama clan as a commissioned officer, is responsible for the supposed ressurection of Ryūgen's brother, Gennosuke. He has extremely potent telekinesis powers, which he can harness to manipulate minds and even bend katana blades to deem them unusable to the wielder.
In his past, when Belmondo was just a pup, he was harrassed by a group of Kagerō ganin who were trying to chase him away from their village. One of the ganin impaled his paw with his katana, laughing and mocking the pup for biting the sword in an attempt to remove it from his paw. Soon, a young Gamu comes to his rescue and pulls the blade from Belmondo's paw. Gamu's mother, Honō , steps in to put a stop to Gamu's charade and tells Belmondo to never show his face in the village again.
However, Belmondo didn't leave, for he admired the Kagerō ganin. Even though he was a pariah amongst the rest of the clan, Gamu had always stuck up for him in the end. Because of their friendship, Belmondo was allowed to be raised in the Kagerō village. During their friendship, Belmondo and Gamu often discussed what kind of future they would like to have after their processing ceremonies. Gamu states he would like to become the clouds, to be able to see the world. Belmondo responds that he would like to be the dragon that sits upon those clouds. He became a full-fledged ganin some time later, and was considered the only one who could indeed rival the power of Gamu.
Many years later, he disappeared from the clan and reappeared as an enemy working for the Gama clan. Using his incredible telekinesis powers, he manipulated the dead Gennosuke to infiltrate the Kagerō clan's village and get to Ryūgen under this guise. Meanwhile, while Shiba was on his way to delivering a letter, Belmondo ambushes him, twists Shiba's katana around his muzzle, and attacks him.
Back at the Kagerō village, a wolf howl could be heard. Shiba tries to contact Rando and Gamu, but to no avail, as Belmondo's power is cutting off the communication. When Gamu arrives, he finds his comrade dangling by his leg in the forest, beaten and bloody. Belmondo cackles, greeting his former ally and friend. He reveals that he has gained amazing power, including the secret art of manipulating human minds, through his lord, Gama. He uses his odd double-bladed weapon, a barbarian's sword, as wings as he propels himself through the air, attempting to wound Gamu. In a flash, the image of a dragon appears before Gamu — Belmondo had used the aura from his own body to transform himself for his ultimate attack. He mocks Gamu for never being able to accomplish his own dream, to become the clouds. Gamu uses the leaves to climb through the air and locks blades with Belmondo, forcing him towards the ground. Gamu uses Belmondo's blade to slide his own katana towards Belmondo's head. In one slash, Gamu decapitates Belmondo as his lifeless body hits the ground.
Belmondo's powers are so great, however, that he is still able to use his telekinesis to send a chilling message to Gamu and Shiba. He warns them that it was his mission to end the life of Ryūgen, the leader of the Kagerō clan. Hearing enough, Gamu ends Belmondo's life by impaling his head with his katana. With tears running down his face, Gamu's final wish for Belmondo is to be reincarnated quickly.
There have been many different spellings of Belmondo's name;
however, the correct reading for 白耳 is bái ěr (in Chinese) or ベル beru (commonly transliterated as "bel"). The 白耳 coupling is used in ancient country spellings such as 白耳義 (ベルギー berugii), or "Belgium." The last two kanji in his name (紋怒) are read "モン (mon)" and "ド (do)" respectively as on-readings (original readings based on Chinese pronunciation). 紋 (mon) refers to the family emblem of a family or clan, and 怒 (do) simply means "angry" ("to be offended").