Official art of Mimotsuki (Source)
Mimotsuki is the protagonist of Wakana Nikki.
Mimotsuki has one red eye and one purple, her red eye due to being possesed by Madotsuki. According to Kurorosechan6's description for Mimotsuki, she wears headphones all the time, but this is not seen on her sprite. Her outfit is a black tank top, a short blue skirt, and orange shoes. This sprite is a literal recolor of Madotsuki, as can be seen in the Charset folder by a half-colored-over Mado sprite.
Mimotsuki is described as rebellious, listening to a lot of music (specifically Vocaloid) and watching a lot of anime. She also is shown to be very caring toward her friends, especially Madotsuki. She was heartbroken when Madotsuki committed suicide, causing depression based on her worry for her friend. However, she can also have a distant or cold personality towards some people. She also has a fear of being lost.
Mimotsuki wants to be a surgeon when she grows up, due to her parents wanting her to become a surgeon.
Mimotsuki went to the same school as Madotsuki. When Madotsuki committed suicide, she possessed her to guide her though her dreams, as evidenced by her red eye.