Koshi is Dashi's 10 year old sister who plays detective seen in The Kelp Monster Mystery. She is a fan of mystery novels and is honest and well behaved around others. Koshi helped the octonauts solve a disappearance in the kelp forest and lead the way. She was about to turn 11 years old and is full of kindness.
Koshi has a black shirt with a jade green overall dress with a pocket in the front. The pocket has a pencil and notepad in it. She has brown hair in two ponytails and yellow pearls. Koshi also has brown nose and muzzle. Koshi has yellow tights and green shoes.
Dashi - (Big Sister)