is Naeka's friend and fellow teammate in the kendo club. They are usually seen eating lunch together or at practice with Miwa. Eiko is usually the first to yell at her busty classmate for her shallow or selfish comments. She is highly envious of Naeka's bust size and whenever she gets annoyed by Naeka's comments she commonly assaults her friend by groping her breasts. Her desire for bigger breasts is such that she willingly becomes Urashima Taro's mind controlled slave in exchange for him using his powers to enlarge her bust size. At the same time, Eiko does enjoy her friendship with Naeka, scheming for their kendo club, wanting in on the latest gossip, or needing help with the maid cafe where she and Miwa works.