A hellish creature commanded by the new Hell Girl in season 3, who takes on the look of a young boy, though he can also become a yellow straw doll. In human form, he calls himself by the name of Huang (黄). Often quiet and having a gentle demeanor, not much is known about him as of yet. He follows Kikuri on their assignments in the real world, referring to her as princess. His name is derived from the same name given to a legendary mountain-dwelling creature in Kyūshū from Gazu Hyakki Yakō, an illustrated book on Japanese folklore demons. In episode 6 of Mitsuganae it is hinted that Yamawaro has the power to manipulate objects. In Episode 17 of "Mitsuganae", it is revealed that his name basis holds some truth. He was a ghostly boy who roamed a mountain but whenever he was seen by humans, he looked like a walking pile of mushrooms. It seems in his time before joining Hell Girl, he looked upon a family by the name of Ashiya. Their son Hikaru had gone missing many years ago. The father of the household was a scientist trying to obtain eternal life. Yamawaro stepped in as their son. Ms. Ashiya accepted him with no worry. Mr. Ashiya, knowing that Yamawaro was obviously not human, used Yamawaro for his "Caterpillar fungus" experiments which still manifests in him till this day. He stated it was "to extend his wife's life". After learning of this, Ms. Ashiya shooed Yamawaro away, hoping to spare him from the parasitic experiments at the cost of her own life. She contacted Hell Correspondence to gain revenge on her husband calling it "Hikaru's vengeance". Despite Yamawaro's begging, she pulled the string. Yamawaro watched as the Ashiya mansion swirled away into a cloud of dust. Ms. Ashiya along with it, clutching what seems to be a young boy. This was a key experience to Yamawaro. After Yuzuki becomes Hell Girl, he and Kikuri simply walk away. He is not seen again until The God of Hell possesses Kikuri. After this happens, he returns and helps save Yuzuki from the grasp of The God of Hell by using a powerful supernatural blast. He comes to the aid of Ai again at the end of the third season.