Ісодзакі Ідзумі

Izumi Isozaki is two years younger than the other characters and is very much like Itsuki Akiba. However, she isn't as shy in expressing her emotions, especially her love for Ichitaka Seto. In fact, she announces her love to pretty much everyone she knows. Also, she's more daring and is quite superstitious when it comes to love. She constantly tails Seto, and on more than one occasion, had tried to seduce Seto to go to bed with her in order to prove her love. Izumi persists in attempting to obtain Seto's love and says that she will try whatever it takes to get him to be with her.

She is introduced half-way through the manga, where she meets Seto on the beach on their summer vacation, and after that, she discovers that they go to the same school. She falls for Seto after he defends her from her overly-aggressive boyfriend, and tricks him into going on dates throughout the series. She is determined that he is her soulmate, and she wants him to be her boyfriend.