Yakui-san is a very popular if not most popular Nijiura Maids in the west. Her name comes from "Yakuji" (やくじ, "Medicine"). She is addicted to pharmaceutical drugs and is often pictured drooling or vomiting with a crazed look in her eyes.
She was kicked out of her parents' house because she was messing with the products of her family's drugstore. Her knowledge of medicines is top-notch, ranging from happy powder to drugs undergoing clinical trials. She has access to both legitimate and illegitimate drugs, and is also able to prepare her own original preparations.
Once a month, she is tied up and de-medicated to make her more mature. The handcuffs on her arms are a remnant of that time.
