Summer of Horror Series - Ghost Story! Cow God Man (夏の怪奇シリーズ - 怪談: 牛神男 Natsu no Kaiki Shirīzu・Kaidan Ushigami Ōtoko) is the 16th episode of Ultraman Ace. It is the second of the 3 Episode Story Arc Summer of Horror Series (夏の怪奇シリーズ Natsu no Kaiki Shirīzu).
Yoshimura was given a holiday break by TAC and ride a train to Okayama. While in the train, a man named Takai seat next to him as he went to the same destination with Yoshimura. Once the train stopped at a destination, they went out of the train together and visited a hill made of over six million bull nose rings. Takai stumbled upon a nose ring, believed to be from the Nose Ring hill and picked it, wearing it as a good luck charm bracelet. Yoshimura warned him to return it but he refused and rode his car while bidding farewell. While driving, the nose ring suddenly tightened, making his car crashed a tree.
Later at his shop, Yoshimura decided to stay with Takai's mother in order to take care of him. A man in purple japanese traditional clothes with a straw hat appeared passing through and call forth the nose ring's curse. At night the same mysterious man ringed his khakkara, making Takai's right hand that wore the nose ring grow furs. The next day, he ring his khakkara again as Takai realised that he grew bull horns on his head and maddenly ran away from his house. He begins to act in a similar manner to a bull by eating olive tree branches and grass and even communicate with a cow. He goes back to the Nose Ring Hill and ask for forgiveness but the man in purple refused and turned him into a choju named Cowra to rampage at the city and feed on human beings. TAC detected the choju and and deployed fighter jets to attacked it, only to be stopped by Yoshimura whom remembered the choju as Takai.
The next day, villagers made a prayer for Cowra to stop as the monster bow to them but the man in purple disrupt the prayer and set the Choju on rampage again. Hokuto and Minami transformed into Ultraman Ace and battled the Choju. Yoshimura noticed the nose ring at Cowra's right hand and ordered Ace to remove it. He does so by kicking it out, then materialised a nose ring on Cowra's nose before he throw the Choju as it turn back into Takai. The man thanked TAC and Yoshimura as he resumed his normal life as a farmer.
- Ultraman Ace Volume 4 features episodes 13-16.