Toeni is Hitoshi's A.I. Program No. 20 (Nanbā Tōenī "Number Twenty"). He based her face on Kimika Aso, the breasts on Reiko Satou, her butt on Ai Iijima, and her legs on Chisato Moritaka, giving her the measurements of 86-59-88 cm (34½"-23½"-35"). However, despite the fact she worked, she teased him a little too much, and though the teasing was good-natured he couldn't handle it in addition to the pressures of school, so he stored her away.
Due to another freak lightning accident Toeni is also brought into the real world, where she too stays with Hitoshi just like Saati ( Who refers to Toni as onee-sama, the Japanese term for "big sister").