She is the main character in the story. She was given the nickname "Yankumi" by the class. She is the homeroom teacher of the class 2-4 in the Shirokin Gakuen. Even she looks like a weakling, she is a very powerful and strong woman. She is the heir to a Yakuza group and she keeps hiding her true identity from her students and the other people in school.

He is handsome, intelligent, rich, kind,... what more could you ask for? He is an introvert.  He is the leader of the class 2-4 and is very popular to the students. He punched a teacher during his grade school to defend his friend. The first time he met Kumiko, he somewhat felt that there was something different about her. He's the first one who found out Kumiko's true identity.

He's called Kuma/Bear. He is Shin's best friend. He calls Shin "Shin-chan." (This reminds me of that anime... Shin-chan.. y' know that? I think its Crayon Shin-chan.) He was with him since grade school. His mother was saved by Kumiko from some guys.

He is one of Shin's friends. He always gets into fights, like everyone else. He had a fight with Tsuruta Ichiro, and was beaten by him. He was the one who thought of rescuing Shin in episode 11.

He is also one of Shin's friends. He was the one who thought of giving Kumiko "Yankumi" as her nickname. He was suspected to be the thief in the episode where Kumiko became blonde.

He is the guy with a weird hairstyle (heheheh..). He's also one of Shin's friends. He was lost in Okinawa when they had a trip there and he gave Kumiko and Shin a lot of problems during that time. 

She is a music teacher. She has a nice body (even I don't think it's nice.) and is admired by lots of students because of it. One of her students before committed suicide and she learned a lesson because of that incident. She likes handsome guys. She started a choir club in school.

He is Kumiko's old dog. He narrates the preview for the next episode. He is very loyal to Kumiko. He talks most of the time even nobody can hear him.