Although Maiko Yanagihara could have done anything she wanted, she followed her family's tradition of teaching. Not surprising, since her education included literature and language. She was well-respected and she kept a strict classroom, never tolerating any moral variance in her students studies.
Yanagihara did have one weakness though: she liked chocolate. It was on a rainy day that she was at the store and did not have enough money to get a candy bar, so she shoplifted one bar. At first, she thought nervously she had gotten away with it. But as it happened, just as she left the store, three of her females students had approached her. The three girls always shoplifted for kicks, so they found it amusing that their strict teacher had shoplifted also.
That was the last time Yanagihara stole anything. However, the three girls never let her forget that they knew her secret, and done so by maliciously sending her secret notes and stolen gifts to remind her. The strain from this was more than she could bear... making her the target for the shimna Ga-Ryu. The monster sensed Yanagihara's distress and offered to get revenge upon her tormentors. In exchange, it stayed at her apartment, disguising itself as an iguana.
Soon, the three girls, one at a time, suffered horrifying deaths similar to vampire attacks - they were drained completely of blood. However, this drew the attention of Miyu, along with Larva and Shiina, who disguised herself as one of the students in the school Yanagihara worked at. This also caught the attention of another student, Nobuo Machiyama, who had witnessed the aftermath of the first killing - and Miyu!