Fanart of Misotsuki. Source
Miso (みそ) = Miso soup + tsuki.
Misotsuki (みそつき) is the protagonist of the legendary Miso Nikki (みそにっき).
She is said to be a character with a design similar to Madotsuki's, only with bigger breasts (because of her ASCII Art).
Not much is known about her because she is just a joke from a 2ch meme, but one thing for sure she loves Miso.
Very little is known about Misotsuki, as her game was taken off the internet more than five years ago.