Fumika is the main character in the anime series. She appears to be a young girl, though her real age is never mentioned. She works as a mail carrier from the afterlife realm of Shigo, delivering what are known as "shigofumi" to people in a Japanese city that she has been assigned to. These shigofumi are letters written by those who have recently died, and it is Fumika's job to deliver the letters to whoever the dead wanted them to go to. Though typically the shigofumi mail carriers are people who have already died, and thus do not age, Fumika is different in that she ages at the same rate as a normal person, signifying that she has not died yet but is merely in a state of astral projection.

Fumika is almost always calm and speaks in a low monotonic voice. She is serious about her job and carries out her duties even if it takes her longer to deliver a given letter, such as her having to follow the recipient by train to another part of Japan. She does not like normal people interfering with her work, and often has to resort to violence or threaten others with a large gun she carries in order to complete her deliveries. Due to her unusual occupation and the uniform she wears, she is generally not taken seriously when she tells others that she is delivering an "after death letter" to them, but continues to persist until she has handed over the letter. The only time she shows any expression is when around cats which make her very agitated to the point of her losing her composure entirely.

While still the main focus in the light novels, her character is somewhat different. She still appears the same and generally carries the same personality, though Fumika in the novel, for one, hates all insects vehemently and will not even go near them. She loves to play shogi (Japanese chess), though she plays on intuition alone.

Fumika actually suffers from dissociative identity disorder due to the abuse from her father, Kirameki Mikawa, while growing up. The two personalities are Fumi and Mika. Mika is the shigofumi mail carrier that takes her job very seriously; and Fumi is a kind, outgoing young girl. Mika is the one that shot Kirameki when he tried to kill Fumika when she made him remember her mother. Fumi blamed herself for the shooting, withdrawing to a coma-like state, causing Mika to "die". Mika has since somehow come into contact with the Gospel Department and enlisted as a mail carrier in order to await Fumi's return, gaining a separate existence in the process. Mika has stated that even her words do not reach Fumi.