A 16-year-old-girl who ends up as Seiji's right hand. She has had a crush on him for three years. One day she wishes to be with him so much that she finds herself, in miniature form, in the place of his right hand. This causes problems for him, since it is the "Devil's right-hand" he punches with. Midori's real body is in a coma, and her mother tries everything to bring her back. As soon as Midori finds out that she is on Seiji's hand, she gathers the courage to admit her love, even though it isn't requited. During the series she continually confesses her love, and gets jealous of other girls, often trying to compete with them. Over time she begins to like qualities of all of the characters. Her personality is shy at first, but when she gets to know people she lightens up. During the course of her days with Seiji, she wakes up in her normal body a few times (during which Seiji's right hand reappears), but then she feels lonely and returns to a comatose state.

Midori appears to be a fun, carefree girl, but as time progresses it is shown that she is actually a little bit more shy than she lets on (she mostly doesn't show it because she has been spending so much time with Seiji). Some emotions she hides well is her jealousy towards the other girls Seiji comes in contact with and her determination to win his heart.