Mayoi is an 11-year-old girl who stands at 4'9". She consistently carries a large backpack, wears a hairband, and sports ponytails. As for her personality traits, she is lively, spirited, and inquisitive. Despite being young, Mayoi often makes spelling errors and mispronounces the Koyomis family name. However, she tends to be cautious around strangers and may even defend herself if they become too intrusive.
Ten years ago she was involved in a traffic accident and died because of it. After that she became a ghost and considers herself a "lost snail." She unwillingly causes the people around her to become lost and unable to find their way home. The only people who can see her are people who dont want to go home in the first place.
In Shinobu Time, she is chased by the darkness together with Koyomi Araragi. It is later revealed by Izuko Gaen that the darkness was targeting Hachikuji because she remained in the town even after she was saved by Koyomi. To stop the darkness, she finally decides that she must pass on. She kisses Koyomi and confesses her love for him before she vanishes.
Ten years ago she was involved in a traffic accident and died because of it. After that she became a ghost and considers herself a "lost snail." She unwillingly causes the people around her to become lost and unable to find their way home. The only people who can see her are people who don't want to go home in the first place.
However, after Araragi and Senjougahara help her find the home she was looking for, she changed from an "earthbound spirit" to a "wandering spirit," a fact that she considers to be a bonus, as well as granting her to be free to wander wherever she desires. At the end of Nisemonogatari, she said goodbye to Koyomi, implying that she will not be seeing him again, which will be the basis of the next story, Mayoi Jiangshi. Her family name before her parents got divorced was Tsunade.