Eriko Hinamori (雛森 恵理子 Hinamori Eriko), née Eriko Otomo (大友 恵理子 Ōtomo Eriko), is the the heiress to the Outomo financial empire and a very high-class lady, the wife of Shuu Hinamori and the cousin-in-law of Amu Hinamori who is a one-use anime-only character that appears in episode 35.
Eriko is voiced by Aya Endo.
Eriko met Shuu Hinamori when he accidentally knocked on her apartment door, when she was studying in Paris. He was holding a basket of freshly-baked Melon pan/Melon bread that he was supposed to give to his cooking teacher. Upon recognizing the Melon pan/bread, Shuu asked Eriko if she would like to try some where she ate one and she said that it reminded her of falling in love.
At the end of episode 35, Shuu and Eriko get married (which now makes her Eriko Hinamori).