She loves cosplaying. She might look like she’s around 10, but she’s actually 24. This is more apparent when the ears on her "neko" outfit fall off. During the day, she’s just an ordinary office lady who is more often than not absorbed into cosplaying. She even draws her own doujins and tries to sell them at Comiket. She has deep knowledge in Super Sentai, but nowhere as deep as Akagi. Also, she is a fan of Shonen-ai/Yaoi (boy love). She also has a sort of interesting form of affection towards women.
Yumeria was the last of the three to be recruited by Hiroyo Hakase.
She is quite the master of character change as when she changes costume, her countenance and behavior also changes, concealing her real persona which she barely shows. Her few persona changes are:
- as a lolita cat girl
- as a cyan or blue-haired young schoolboy
- as The Mad Hatter from "Alice in Wonderland".
- as Mele
- as an alien
- as a witch
- as Satomi Funabashi from the Z-Cune Aoi anime.
- as a Sailor Senshi/Shogun amalgam
- as a bee
- as a rabbit girl
- as a geisha
She can also take on various personas to be in-character when trying out new costumes.
Yumeria inherited her love of cosplay from her mother, Masako Yamada, who herself was a famous cosplayer. The two were very close, and Yumeria intended to show her mother around Akihabara until she was killed in a car accident. Due to their close bond, each year on her birthday, Yumeria imagines herself celebrating each birthday with her mother.