Umi has thick curly blonde hair with side bangs and she is known for her iconic "eye smile".
At the school, she is normally seen wearing a tracksuit, while at home she wears more casual clothing.
Like Takuma, Umi has a bright and bubbly personality. Ever since she was a young child, Umi has rarely been seen without a cheerful smile on her face. She has a generally more relaxed and calm approach to parenting, especially when compared to her husband, Kousuke. She is a very maternal and comforting presence to her son, Kazuma, who cries easily.
Umi cares a lot for her family, letting her eager sons run their first errands by themselves (with Kousuke following them to keep them safe). She trusts her husband greatly, especially when he felt guilty for having to kiss other women as an actor.
Umi is married to Mamizuka Kousuke, a famous and well-recognized actor. She has two identical twins named Takuma and Kazuma. Takuma inherited his mother's carefree and bubbly attitude, while Kazuma has his father's fearful and worrisome attitude.
- She shares the same voice actress with her son, Takuma.