Yamaiko (やまいこ) is one of the three female guild member of Ainz Ooal Gown and regarded as one of the Forty-One Supreme Beings by the NPCs of the Nazarick. She is the older sister of Akemi and the creator of Yuri Alpha, Decrement and Increment. Yamaiko is a Nephilim just like Warrior Takemikazuchi. Yamaiko has a kind and gentle personality. She talks politely and has a friendly relationship with her guildmates. However, she tend to do things before thinking things through, earning the title: muscle brain sensei. While so, she has a tremendous mental fortitude despite people comparing her to her young sister.