Chiyo was a soratami prophet, tactician and warrior from Kamigawa. She was the most advanced disciple of Uyo, the silent prophet, and a devoted follower and a right hand of Mochi, the Smiling Kami of Crescent Moon, the patron spirit of soratami.
She was ruthless and cunning, capable of armed fight and short-range psychical attacks. However, one day her path crossed with Toshi Umezawa's, when Toshi accidentally confronted two of her agents and defeated them. Chiyo set an ambush in Toshi's house, and she would have been successful, if not for a "backup" paralyzation kanji built into the roof. Again, Toshi escaped the soratami and embarrassed her. She promised revenge on him. But it was Toshi who surprised her the next time, when he appeared in the very seat of soratami power, the Otawara palace. Blind with rage and anger, Chiyo fought Toshi, but was defeated by the cunning ochimusha. In addition, when she tried to crawl away, Toshi released an oni-dog from a spell-tile given to him by Hidetsugu to finish her.
Chiyo survived the attack of the demon dog, but her face was ruined forever - she lost an eye and her nose was broken. From this point on, she wore a silver crescent moon mask. But there were still more bitter pills to swallow. First, Mochi forbade her to pursue her personal vengeance on Toshi, relying on his subtle intrigues and Uyo's tricks. But even Mochi underestimated the power of the Myojin of Night's Reach and her bond to Toshi, and Chiyo was forced to watch helplessly when Uyo's trick backfired on her and she was frozen alive by Toshi's stolen might of the yuki-onna. After that, Mochi finally allowed her to go and kill Umezawa.
The soratami armada in Jukai was destroyed. The balance of the world was restored by the destruction of O-Kagachi and Konda and the ascension of the Sisters of Flesh and Spirit. Mochi has paid for his sins in blood and flesh. Without both masters and army to lead, and with the soratamis' plans ruined, Chiyo finally got what she wanted, when she ambushed the tired Toshi Umezawa and stabbed him through his lungs. Unfortunately for her, the Myojin of Night's Reach decided to forgive Toshi for his previous disobedience and allowed him to choke Chiyo with solid darkness, saving him for her future plans.