Junko Miyaji is Naota's eccentric sixth grade teacher. Her students have given her the nickname "Miya-Jun".
Miya-Jun seems to be constantly troubled by the shallower problems which Naota seems to create, such as the destruction of her car (which happens twice over the course of the series) or the terrible interruption of a lesson. Even on 'normal' days, however, she is pathetically inept: her attempt to teach chopstick usage to a generation of students raised on sporks ends with the revelation that she is unable to use them herself.
She can be viewed as symbolic of the ineffectiveness of educational institutions imparting any truly important or useful knowledge. Naota constantly characterizes the adults around him as "unable to grow up". In his mind, Miya-Jun's inability to act like a normal adult (similar to his father, grandfather, Ninamori's father, Amarao, and many others) confirms his theory. Adults like her are contradictions in Naota's life; he wants to become an adult, but the adults around him don't act like adults at all.
A recurring gag is Miyaji's car being destroyed by a Medical Mechanica robot. In episode 3, her new red Volkswagen Beetle is crushed when Canti jumps down on it from the school's roof. In episode 6, she has replaced the car with an identical one, but it gets eaten by the Terminal Core.
Miyaji appears incredibly young for a teacher, both as a result of her natural appearance and youthful style. She keeps her short black hair up in messy pigtails or a messy bun with brown ties. By her temples, various clips, including a light-blue star, keep the rest of her hair out of her face. Her long, thin black eyebrows arch upwards over large green eyes with small eyelashes. Her earlobes are studded with a pair of small, light-blue orbs. Her outfit changes with every appearance, but is consistently casual overall.
She has a very happy and care-free personality when things run smoothly, but quickly gets frustrated if her students or the topic being taught are difficult. She tries to teach her students life skills, but seems to overestimate her abilities when picking what to teach. Once, when some of the boys were passing around a porn magazine, she confiscated it and went through a series of cartoon-ish emotions upon looking at it before angrily banning outside reading materials for the whole class. She is notoriously unlucky in regards to the events of FLCL, losing her car a number of times to robots and getting reasonably upset as a result.
- The chalkboard she teaches in front of is usually covered in messy art, often of cats, and kanji.