This is the name of a humanoid monster in the legends and folklore of Japan. The Kudan is described as having the body and legs of a gigantic bull with three eyes along each side and a row of horns protruding from its spine. It has the head of a human. It was regarded as a beast that could never deceive and always told the truth.
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army
Kudan is a rare random enemy. In order to fuse Kudan, Raidou must defeat one in battle in order to claim the key item she drops, the Prophetic Book. Kudan, however, cycles weaknesses, has a large pool of HP, knows Diarahan, and will often try to escape rather than allow itself to be defeated. The Astral Burst combination attack is a virtual necessity to defeat her.
Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon
"A cow with the face of a human that can speak human languages. It's born from other cows. It's said to be a terrible omen; it leaves a prophecy certain to come true, then dies."
—Gouma-Den Devil Chart
Persona 2: Innocent Sin
The rumor for Kudan can be obtained from a man in Sumaru TV after completing Caracol, however its head cannot be traded for anything.
Persona 2: Eternal Punishment
The rumor to make Kudan appear can be obtained from Yasuo Inoe in the Bomb Shelter. Kudan can be found in the sixth area and drops Kudan's Head, which can be given to Yasuo for a Mutation Gear, Syncronize Gear, and Adjustment Gear.
Stats
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army