Princess Mikotsu (in Japanese: 海骨姫) is the secondary antagonist of Wadanohara and the Great Blue Sea. She is a former princess of the Sea Kingdom and was sealed away by Meikai after losing a war to Princess Uomi, her sister.
Princess Mikotsu is seen with dark grayish blue hair that is put into long pigtails. A skeleton fish sits atop the right side of her head and often speaks for her, just as her sister Uomi. She wears a kimono, similar to Tatsumiya's, except it is a dark gray with a skeleton fish on the middle part with red outlining. White lace adorns the hem and part on the mid section of her kimono. Her eyes are red and she appears to have bandages wrapped around the right side of her face, covering her eye. She also has hands with no flesh, resulting in a skeleton-like look, which is the same for her arms.
Mikotsu normally didn't talk she herself, often having Skeleton Fish verbally communicate with the others. But she is shown to have a strong hatred for her sister, Princess Uomi, and is also shown to be sadistically merciless. When the player fights her, damage is done to her, but even continuously spamming Moonlight Seashine/Feeding Frenzy, Ultimate Momecha, Killer Dolphin Show, and Kraken wouldn't kill her, and she has immense power. However, in the bonus room video, it shows Mikotsu locked up and speaking in her normal butchered sentences, asking questions like "fAthER ... wHy ... iT hUrtS ...", and when Uomi and Mikotsu were fighting, she even said "faTHeR ... WhY ... ?", which concludes that Mikotsu dearly loves her father but is deeply hurt that he chose her sister over her.
- The kanji that make up Princess Mikotsu's name, "海骨", translate to "sea bones".
- Mikotsu is the only character to talk in butchered sentences continuously throughout the game, excluding Wadanohara's butchered speech for little time in the game, using speech such as "fAthEr... wHy...?"