|Allies||Tamon Takeuchi, Akira Shimura, Kyoya Suda|
|Voiced by||Masami Mizuno|
The night before the first day, at the 23rd hour, Yoriko was sleeping in the passenger seat of Takeuchi's car. Takeuchi snuck out of the car without her noticing. An hour later, she left the car after realising that Takeuchi was missing. While searching and calling out for him, a siren rang before an earthquake caused her to lose consciousness for two hours.
At the 12th hour, unable to bear the dryness of her throat, Yoriko tried to drink from a spring on shrine grounds, but this angered Takeuchi, resulting in her being left behind. An hour later, Yoriko searches for her student ID. 16:00, Yoriko was discovered by Shibito, and startled and in a panic, she attempted to flee when she was saved by Akira Shimura. She also displays a self-sacrificial mentality when she uses herself as a decoy to help out. Yoriko then bore witness to the umi-gaeri at the edge of village. Shimura, whom had been accompanying her, committed suicide. Despite being shocked, after a few hours, Yoriko finally reunited with Takeuchi.
Day 2 on the 16th hour, Yoriko and Kyoya are taken to hospital by Miyata. Kyoya's blood enters Yoriko, and she too inherits immunity to transforming into a Shibito. Four hours later, she infiltrated the Shibito Nest with Kyoya, and through her quick thinking, secured a path. By midnight, they arrived at the Mirror Pool, present at the descent of Datatsushi. They were attacked by Datatsushi when Takeuchi saved them.
18:00, Yoriko found Takeuchi inside the nest, but loses sight of him in a muddy cascade.
Later, at 4:00, she breaks into the Takeuchi house to discover her teacher in an entranced state, and after beating his Failed-Shibito parents with a baseball bat, she pulled him away.
Yoriko has a huge crush on her teacher, and she is quite abrasive and hysterical at times. However, she has a good heart, and has a surprising reserve of courage when called upon to fight.
- Student of Tamon Takeuchi; has a crush on him
- Saved from Shibito by Akira Shimura; later shot by him
- Received a blood transfusion from Kyoya Suda, making her immune to turning
- Yoriko is a student at Josei University, her student ID number being 310705. She is majoring in Folklore Cultural in the Anthropology Department of the School of Humanities.
- Yoriko attempted to write and send a postcard to her parents, revealing that she departed on her journey in the middle of the night to assist one of her "professors with his research". Her mother and father are named Hideo (秀男?) and Masako (正子?) respectively, and they live in Shinagawa.