Aniyaku is a minor character in the animated film Spirited Away. He serves as the assistant manager of the bathhouse, a position that places him in a role of authority among the facility's many workers. His name is derived from a Japanese term that roughly translates to "elder brother role," which reflects his position and seniority.

In appearance, Aniyaku is a spirit who resembles a large, upright frog, similar in form to many other male employees of the bathhouse. He has small, distinct black eyebrows and a neatly kept mustache. His typical demeanor is serious and businesslike, befitting his management status.

Initially, Aniyaku treats the human protagonist with harshness and open disrespect. Like most of the bathhouse staff, he harbors a strong prejudice against humans and is unwelcoming to her when she first arrives and begins working there. This attitude reflects the general insular and discriminatory culture of the bathhouse's workforce.

However, Aniyaku's attitude evolves over the course of the story. He is present for the major crisis caused by the No-Face spirit, who begins consuming workers and wreaking havoc in the bathhouse. When the protagonist successfully confronts and pacifies No-Face, effectively saving the staff, Aniyaku is among those who gradually come to accept her. He joins his fellow workers in cheering for her, showing a significant shift from his earlier disdain to a form of grudging respect and gratitude.

Aniyaku does not possess any overt magical or supernatural abilities. His power comes from his role as a manager, where he is responsible for directing other workers and maintaining order. He is known for a particular lyrical or rhythmic style when issuing commands to the staff, especially when directing them to cater to the demanding and wealthy No-Face. He shares a close working relationship with Chichiyaku, the other manager of the bathhouse, and together they represent the mid-level authority figures who enforce the rules set by the witch Yubaba, the establishment's owner.