Cool Teacher: Tells her students to have fun as much as possible, and it can be hard to tell her apart from her diving students
Stern Teacher: But she is very strict when it comes to actual teaching, bordering on sadist, especially when teaching diving.
Genki Girl: While being in her early twenties she can give even Pikari a run for her money.
Hot Teacher: Does not seem to be much older than her students, and quite a bit of fanservice comes from her.
Sensei-chan: Normally a responsible adult, but she can be pretty childish sometimes too. Like, getting really into a race across town, bending the rules of a children's game so she wins, and not wanting to pay her debts.
Transplant: She seems to be the same character from Amano's older manga Roman Club, where she is the main character's older sister.