Kyouko's young brother. He sees Kyouko as a motherly figure because she has been the one taking care of him since he was born because of the nature of their parents' work. In the beginning of the story, he is brought back to the Hori household by Izumi after he had fallen down on the street. Since then he has been very affectionate towards Izumi, going as far as calling him a non blood-related brother.
Shigeru J� joins the evil organization Black Satan after the death of his close friend Gor� Numata, who he considered his mentor. He, promised power, and fueled by a desire for revenge, undergoes surgery to become one of Black Satan's super warriors. However, Shigeru knows that Black Satan were in fact the murderers of his friend; he was using Black Satan in order to gain new powers. The newly powered up Shigeru escapes from the Black Satan headquarters before they can brainwash him into following their campaign of evil and becomes Kamen Rider Stronger.
A sickly girl who arrives later in the manga because she has been hospitalized since before the start. She appears to be Kawai's opposite in every way as she is cheerful and popular. When she first returned to school, she noticed the necklace the teacher took from Kawai which he then gives her (seemingly as a way to get Kawai expelled in hopes she would attack Hana to get it back), however, she instead tries to befriend Kawai which goes well. Until she discovers that Yuusuke confessed to Kawai, as she has feelings for Yuusuke and even asked earlier if Kawai had feelings for him, which she denied but believes she is lying. Because of her outbursts, Kawai believes that she is only doing this because she likes the attention. Which maybe true as with anything that happens she is prone to emotional outbursts that get the rest of the classes attention in the matter, shown where Kawai causally pointed out that the cross was missing from the necklace, only for her to have an emotional outburst about it being missing. At the end of chapter 17 it appears that Hana is losing her sanity, smiling evilly with a blank look in her eyes. Later she conspires with the classmates against Kawai to have everyone hate her by setting her up with vicious comments about the other students in her bag, however this seems to quickly falls apart when Shin points out that she says what she feels without hesitation and wouldn't write that, as well as Kawai seeing through Hana's "help". However, later she sets Kawai up to make it look like she really did write it and ultimately suggests splitting up the group. In the end is stated to be the head of the group. This causes Kawai to show aggression for the first time, as she was truly dedicated to her role as the Choir Leader and correcting Hana when she thought that Kawai hated her, where she just didn't see her as a friend, calling her a Bad Friend. However, Hana finally shows her true colors and confirms that the teachers only set up Kawai as the Leader as a way to promote the school. Hana makes a conspiracy against Kawai to make herself look good at the choir competition. Hana finds out that reporters are going to be there. She gets even madder when Kawai ruins her plan 'accidentally' and bursts with anger in front of the camera. The reporters realize that Hana and everyone are misunderstanding Kawai.
Ayucchi cares a lot about how she looks and takes a long time doing her makeup and hair in the morning. Because of Ayucchi's ego and jealousy over Kawai's looks, Ayucchi tries to make Kawai look bad in front of the class. Kawai's classmates, excluding Yuusuke and Shin, start to hate Kawai even more because of Ayucchi. But when Kawai's words help Ayucchi confess her love to Yuusuke, Ayucchi realizes Kawai isn't too bad.
A former friend of Maria's from St. Katria Girls School.
One of the three strongest. Consists of a male half and a female half joined together.
A son of Yu-baaba. Judging from his appearance, he is probably a baby, but he is quite huge, and he eats enormously. He is quite spoiled as Yu-baaba dotes on him.