Mizuho is the main protagonist who transfers to an all-girl's school per his grandfather's will and must crossdress in order to attend. He already looks very androgynous, so the change thankfully isn't obvious to the other members of the school. However, Mizuho is always nervous about being found out and constantly worries that it will happen. In spite of this, he was well received on his first day at school and has already become very popular among the students. At first he was shocked when he found out about the will, but with the help of his childhood friend Mariya Mikado, who also attends the school, he was able to resign himself to transferring to the school. Despite making the change, he still uses language which is usually only used by males in Japan such as boku (僕), meaning "I".
When Mizuho was younger, he had very little self-confidence and in effect often would follow Mariya around, depending on her as his closest childhood friend. Additionally, his mother died from an unexplained illness when he was younger and one of her last requests to her husband, Mizuho's father, was to not force Mizuho to have his hair cut until after he had grown up. Mizuho explains this was so that he would be free to make his own choice of what hairstyle he wanted later on, and obviously he kept it, thinking it suited him best.
Mizuho's had to use the surname Miyanokōji, his mother's maiden name, in order to enter into the school; his actual surname is Kaburagi (鏑木). The Kaburagi family's biggest rival is the Itsukushima family, both of which are very well-endowed in terms of money and power. Mizuho didn't realize it at first, but Takako is a member of that Itsukushima family. Despite this, Mizuho doesn't see her as a rival and enjoys her company very much. In fact, they share Japanese history class together and sit next to each other. They often talk to each other during class by either whispering or passing notes.