A timid girl who is a big fan of Maria. Volume 2 spoiler:
She is actually Ryuu Miyazaki's younger sister and the owner of the box 'Week in the mud'.
When their parents got divorced and her mother got in a relationship, their new father, Yuhei Ishihara, started beating Riko up because of her nature. At some point she snapped and she and Ryuu murdered their parents.
During the opening ceremony at high school she was enchanted by Maria Otonashi and wanted to be closest to her which led her to take hold of Kazuki Hoshino's body as he was the closest to Maria.
At the end of volume 2 Riko Asami drops out of high school and there is a rumor that she is living in Hokkaido and working in a farm.
