Kazuo Noguchi is a supporting character in the anime First Love Monster. He is a male student with blue eyes and purple hair that falls to his neck. Among his group of friends, he is distinguished by having the appearance of a very young child, looking significantly smaller and younger than his actual age. He is a classmate of the main character Kanade Takahashi. His birthday is January 8, making his zodiac sign Capricorn, and his blood type is A.

Kazuo is known amongst his female classmates by the nickname "Koichi-sama". His personality includes a quiet and somewhat sharp-tongued demeanor, which contrasts with his small stature. He is part of the closeknit group of friends that includes Kanade, Tomu Kaneko, Ginjirou Sannomiya, and Kouta Shinohara, serving as one of the primary support characters in the story. This group of elementary school students, who all have the appearances of older teenagers or young men, is central to the series' dynamic as they navigate their unusual friendship with a high school girl.

One of Kazuo’s most notable personal motivations is his particular fondness for his friend Kouta Shinohara when Shinohara wears girls' clothing. This interest is a recurring character trait within the group's interactions. Additionally, he is accompanied by a butler who is described as being possessive of him, highlighting an aspect of his home life and the affluent or unusual circumstances surrounding some of the characters. Throughout the series, Kazuo does not undergo a significant personal transformation but instead maintains his role as a deadpan and observant member of the group of friends, contributing to the comedic situations that arise from their childish behavior contradicting their adultlike appearances.