One of the 4 major 'villains', Mei is the faithful yet easily repulsed maid of Itami Asaguroi, always ensuring to get every task and responsibility done.

Age 23, with a height of 5'0, making her the shortest out of all characters. Despite that, she's incredibly diligent and determined to ensure that tasks are done without fail. However, Mei has also been described to retain a strict, stern, and easily repulsed demeanour, often times she would get annoyed at even the smallest inconveniences. While Mei does care for the people that she cooperates with (to some extent), she's not very friendly - lashing out or shouting at incompetent workers or people she generally can't get along with. Mei radiates a very intimidating presence; employees at the company she works at would be afraid of approaching her, let alone talk with her. Mei primarily works alongside Itami, joining her in their annoying ploys to attack or humiliate Yora and her friends. The two would get into a lot of arguments, either verbally or physically, but despite this Mei looks up to Itami very highly (both figuratively and literally), even though Itami tends to have very immature ambitions.

Before her affiliation with Itami and her company, Mei was admirable and optimistic. She hasn't had an opportunity of pursuing any other career, only servitude was available and it was forced upon her, so she didn't have much of a choice. She started working as a maid at an extremely young age, and a majority of the people that she had worked alongside were also maids and butlers at work or in training. She's incredibly adept in many household tasks, along with other skills, but her client search streak wasn't as fulfilling as she had hoped. Almost every one of her clients was either manipulative, violent, or corrupt; out of all the maids, she probably has it worst. As her association with working with more bad-hearted clients continued, it slowly began to change Mei's personality, from optimistic to cold and abrasive. She had to quickly cut ties with all of them before things could get worse. Most of her methods of 'quitting' were usually normal discharges. Other times it got very violent.

Throughout her entire career of serving people, she had worked for a total of 13 clients. The former 12 noted as "disgusting", as Mei would crudely describe. She began to lose trust in others, and faith in herself began to dwindle. Eventually, she managed to find a job at ASAGI Tech. Company, where she'd end up working with Itami Asaguroi, her 13th client and her current one. Much like her other clients, she too was cunning, manipulative, and devious, but she was different. Itami holds good regard for Mei's well-being, despite the many fights and arguments they have. Her now warped personality has also benefited Itami whenever the two go out to cause trouble for Yora.

Mei specializes in a multitude of bladed weapons, most of them being needles and knives (and the occasional fork). She keeps two emergency knives underneath her apron. Occasionally, she would also fight with a whip.