|Romanized Name||Mizoko Kooli|
|English Name||Mizuko Koori|
|Affiliation||Twin Pirates, Heart Pirates, Red-Hair Pirates|
|Occupation||Twin Pirates; Vice Captain|
|Epithet||'Mizuko the Water Woman', 'Water Princess'|
|Age||15 (debut), 16 (after time skip)|
|Height||172 cm (5'7")|
|Japanese Name||Mizu Mizu no Mi|
|English Name||Water-Water Fruit|
Mizuko Umi's full name is Mizuko Koori. She is called Mizuko Umi by the Navy and World Government because of her Devil Fruit ability. Mizuko normally wears a light blue shirt with no sleeves and a short dark blue skirt with black tall boots. As a child, her dark blue, wavy hair was tied up in two high pigtails, but changed her hairstyle to letting her hair out, only tying it up in a high pony tail when she is serious (like Roronoa Zoro and his bandana).
She has a twin sister named Kazami Koori who ate the Air Air Devil Fruit and has air/wind controlling powers. Her powers allow Mizuko's water to freeze and allowing them to do fusion attacks, as powerful as Aokiji's ice powers.
Mizuko's devil fruit ability allows her body to become water, since the fruit is a Logia type. Her ability allows her to 'become water' and even though she can be weakened by Sea Stone/Sea Prism/Kairoseki and when she falls into the sea, or rain falls, she can 'become' the rain, yet enabling her to feel what water feels like. When Mizuko is fighting a Devil Fruit user, she can easily suck the water out of the air to enlarge her body or use the water in the air to gather up and shoot at the enemy. No Devil Fruit users can touch her when she is in her solid human form without being weakened.