Subtitle: Child's mind Yokai (童心妖怪 Doshin Yokai)
- Height: Micro ~ 61 m
- Weight: Micro ~ 68,000 t
- Origin: Earth
The monster Yamawarawa lived in the mountains for many years and one day met a boy who was injured. They soon became close friends until one day when he had to leave. The monster then gave him a special tear like rock to remember him. In later time that same man had a family and a kid who then saw the same monster in the cave and they also became friends. Team EYES was then sent in to investigate. The father, despite knowing about Yamawarawa, did not believe his son and they soon took a drive, the monster became angry and grew to a giant size and the kid then went missing and was lead by the monster to his home. EYES soon found them, but the creature became threatened and grew big. Mushashi transformed into Ultraman Cosmos to fight him. Many times Cosmos would be hit by his horns. The giant then went into Corona Mode to gain an advantage. When the father had the chance he showed Yamawarawa the rock that he gave him and he then calmed down and then grew small, Cosmos then left to find the kid, which he did. To this day he has not been sighted by anyone, but still wanders the forest looking for more friends.
One night, Yamawarawa accidentally snuck into a truck and ended up at Mahagera village. There, he was given refuge by some kids. When the monster started it's assault again, Yamawarawa appeared and battle the demon as the villagers cheer for the protector. It was revealed according to the legend, Yamawarawa had once fought the demon Mahagenom and brought peace to the Mahagera village. Cosmos appeared and aided Yamawarawa, giving him some time to charge his greatest attack to seal Mahagenom forever. Yamawarawa bids farewell to the children and went on a journey back to his old village.
- Yamawarawa's suit would later modified into Arakunia from Ultraman Nexus.
- In the credits, Yamawarawa breaks the fourth wall by offering fruit to the viewer.
- Yamawara could've been inspired by the Bigfoot myth.
- Yamawarawa's appearance and episode debut (9) is based on the theme of children growing up as an adult.
- Yamawarawa's return in episode 36 is due to the Yokai's popularity with the staff.
- Yamawarawa appeared in the special King's Jubilee pulling a sled, alongside Miclas and Gubila.
Powers and Weapons
- Size Change: Yamawarawa can change his size when angered.
- Horns: Yamawarawa is armed with horns on his head and shoulders that can be used for goring.
- Seal: Yamawarawa sealed the evil demon Mahagenom by performing a ritual dance.