Masumi Ageo, a 23-year-old kindergarten teacher in charge of the Tulip class, exhibits a nervous disposition and frequently experiences panic attacks when managing large groups of children. Her demeanor shifts dramatically when her glasses are removed, blurring her vision and triggering an aggressive, fearless personality. This transformation was first observed during an incident in which she displayed unusually assertive behavior. Her condition resembles that of a character from the Dragon Ball series. She maintains a fixation on a person named Kuroiso, with the nature of her interest varying across different media—sometimes portrayed as admiration, other times as romantic. Some theories propose a marital connection, though this remains unconfirmed. Over time, she shows a gradual trend toward increased extroversion without fully embodying the trait. She appears in a supporting role in the film *Crayon Shin-chan: Explosion! The Hot Spring's Feel Good Final Battle*, as well as in other franchise films including *Arashi wo Yobu Jungle*, *Arashi wo Yobu Eikou no Yakiniku Road*, *Densetsu wo Yobu Odore! Amigo!*, *Otakebe! Kasukabe Yasei Oukoku*, *Arashi wo Yobu! Ora to Uchuu no Princess*, *Bakumori! Kung Fu Boys - Ramen Tairan*, and *Gekitotsu! Rakuga Kingdom to Hobo Yonin no Yuusha*. Her surname originates from Ageo, a city in Saitama Prefecture. She shares a notable resemblance with another character named Masao. An earlier episode features a nearly identical teacher managing the Tulip class, a reference that preceded her official introduction to the series.