Momoi Ryouko is a teacher at Toryo High School and she is also the women's tennis coach. She is just as popular with the kids as Namura-sensei is. Ryouko and Namura went to Toryo together along with Kijima. In high school, Ryouko and Kijima were a couple. Then she developed feelings for Namura and Kijima had to move to America with his parents. He wrote her after he left and told her to have a good life with Namura. Years later, they are all still very good friends.

Momoi is a very sensitive person who hides her feelings and makes light of difficult things. She is actually an adult version of Miki. Momoi is still very much in love with Namura and tries to tell him. She is shocked when she discovers Namura's relationship with Meiko and tries to get Namura to stay in teaching. She becomes Namura's eyes to watch over Meiko while he is in Hiroshima. Momoi tells Namura that Meiko is finally starting to stand on her own and that she is getting encouragement from Miwa. Momoi encourages Meiko to write and becomes a friend to her.

When she finally loses Namura for good, Momoi goes on a trip to Europe. She has met someone else and needs time to think about her feelings. In the last episode, Momoi and Akira, who just happens to be Kijima's brother-in-law, are still together. Looks like they make it!