Originally appearing as a background character in Season 1, as of Season 2 she is in fourth grade and gains a slightly larger role.
As the twin sister of Kouta, Mitsuki resembles him slightly. She has long brown hair with a few forelocks that stick up on each side of her head. Her eyes are the same color. Normally she is depicted in long dresses with a jacket on top of it, along with ruffled accents to match her socks and a pair of loafers.
Like her twin brother, Mitsuki is a consummate liar and often makes up weird tales or lies. She is somewhat introverted and quiet for most part, just like her brother, but she loves her older sister; as long as she doesn't do anything to damage her teddy bear. She has an innocent atmosphere to her and is slightly dependent on her brother.