|Strength||Incapable of self-defense|
Yui wears the default female school uniform, unless customized by the player.
Before the [History|February 8th, 2016 Build], she had scarlet hair worn in a ponytail to her right. Her eyes were scarlet as well. Her bust size is 0.5, the smallest in the game.
As of the February 8th, 2016 Build, Yui has scarlet hair kept up in a short ponytail on the right with her bangs swept to her left in mini triangle shapes and her eyes are burgundy.
Among the [] currently in the game, Yui is Spiteful. If she sees a [] or witnesses the [] of a student who is being bullied or who is bullying her, she will wink and compliment Yandere-chan on her crime, however then run off in order to not be considered an accomplice. She will not talk to Yandere-chan the next day after seeing her commit murder. If she witnesses the murder or corpse of any other student, she will leave the school and call the []. If the player has their [] aimed at her, she will become annoyed and cover her face. She cannot participate in physical fights against murderers.
At 7:05 AM, Yui enters the school grounds. She walks to her [Room|locker] at 7:10 AM and changes from her outdoor shoes to her indoor shoes. At 7:15 AM, she walks into the [], to the left side of the [], and gossips with Yuna Hina, Koharu Hinata, Mei Mio, Saki Miyu, and Kokona Haruka.
At 8:00 AM, Yui walks into [1-1|Classroom 1-1] and sits at her desk. She starts her morning classes at 8:30 AM, and leaves to go to the [] to gossip with the [Butterfly|Social Butterflies] at 1:00 PM.
Yui walks back to class again at 1:30 PM and participates in [Time|cleaning time] between 3:30 PM and 4:00 PM. Afterwards, she heads to the [Club|Cooking Club] and stays there until 5:00 PM. She then heads to her locker and changes from her indoor shoes to her outdoor shoes, then she lingers there until 5:15 PM, when she walks home.
- Yui's hairstyle before the February 8th, 2016 Build was changed because YandereDev thought that her previous hairstyle was "low budget" and "amateurish".
- Her name is a reference to the most popular female Japanese names in 2012, 1st popular name being Yui, 2nd popular being Rio.
- In older versions of the game, Yui Rio's name was Yui Hirasa. The placeholder name was inspired by Yui Hirasawa from K-ON.
- Her male counterpart is [Yuto|Haruto Yuto].
- Yui used to be in the [Arts Club|Martial Arts Club] until November 15th, 2015 Build.
- Before the June 29th, 2016 Build, Yui used to arrive 2nd to school on the right side, at 7:05 AM.
|“||I thought I saw her with an older man in [Town|Shisuta Town] tonight, but I didn't think it was really her...||”|
— Yui Rio on the [].