Age: 22 Height: 141cm Weight: 42kg Yui is a very quiet, almost emotionless cyborg girl on the outside. After you get to know her though, you realize that her true personality is just like an average teenage girl, and that she's secretly a huge pervert. She's pretty awkward and doesn't really understand how relationships work, but she tries her best to be friendly and kind. She only truly comes out of her shell and shows emotion when her older sister is around, who she is deeply attached to. Yui, together with her sister, was born and raised in the same science facility the Kogure twins escaped from. Her and her sister were extremely close and were always together, until one day the scientists took Yui away without saying anything. This deeply hurt both girls and their personalities quickly eroded away, with Yui losing her emotion and Nami becoming beast-like. Those changes are what led to the procedures the girls had. Yui was designed to be the ultimate super soldier, so she received advanced training in everything the military had available, and at the age of 15, a lot of her body was replaced with synthetic parts causing her to stop growing. Her muscles are more than 50 times the strength of a normal girl her size, her eyes can see infrared and zoom in, and her reaction time is faster than a racecar driver. She still eats food and drinks water, but can survive for weeks without any, and can also go for weeks without relieving herself with no problem, though the massive amount that collects will eventually all have to come out. The facility sent Yui to hunt down and bring back the Kogure twins, but she still had the heart of a young girl who wanted to be loved deep inside her, so the twins instead befriended her and convinced her to stay with them. They taught her lots of things and helped her learn to be "normal" again... in their own way. She slowly started to get her personality back, even if her face didn't show it. The twins were never sexual in front of her, so she didn't pick up anything like that from them. At most, they would kiss, but Yui didn't like kisses when she tried. The one thing that started it all for her was when the twins would pee in front of her. She assumed that was normal, so she would do it too, and eventually the three of them started playing pee holding games together. One day, since she thought it was normal and had never been told not to, she even pooped on the floor, which the twins had never done before that day, but they decided it's alright as long as cleaning it up was Yui's job. All of this eventually got Yui feeling stranger and stranger until she accidentally discovered masturbation when wiping herself clean. After her first orgasm, she suddenly got a lot better at acting natural... and became a big pervert, addicted to anal play and pee holding.