She is a woodwind Instructor brought in by Noboru Taki to help with the Kitauji Concert Band on its path to the national competition. Her main instrument is flute, which she majored in, but she is also highly proficient in all other woodwind instruments. She is the youngest of the four instructors directing the band who is described as gentle with a sweet personality and her woodwind students describe her as a firm but good teacher.
As nice as she is outside of class, Niiyama is revealed to be as strict as Taki and Hashimoto during rehearsal and sectionals, setting extremely high standards for her students and forcing them to practice for hours every day.
