Yumi is a Zess character that belongs to https://www.furaffinity.net/user/themothergoose/.

Formally Dr. Yumi Tenma, a Zess born from her own untimely death to find a cure to "immortality", serving to live out her days as a physician to conduct her medical research and studies.
She has a knack for reading and filling in the blanks of history, but rather of her own perspective.
Yumi is a grumpy and tired woman, with how long she has been walking the living world, she's rightfully so. It is believed that whomever can impress her would be rewarded with a gift.