Mizuki always dresses quite nicely with him being an Idol of the two person group AQUA alongside his best friend Shuuma. Like most of the characters, he is mostly seen in his school uniform, or his casual clothing. Other exceptions are during special events like a concert.
Mizuki is a kind-hearted person, he's like those types of guys that are able to charm girls with their voice ~♥~. He is also a mysterious person, so no one really knows much about him except for his best friend Shuuma. He can also be quite mean because of his painful past. When Hime is around, it hurts him because she reminds him so much of a girl from his past named Sana.
When Mizuki was 10 years old, he met a girl named Sana who was widely known throughout her school for failing at everything. Around that time, Mizuki entered the entertainment business for singing and acting. It was also around that time when Sana realized that she wanted to become an actress. They quickly befriended each other, and Mizuki helped Sana greatly, almost as much as so that it was mostly him doing the work. When he saw how happy Sana was, he started to realize that it wasn't herself that was making her happy, it was him. He knew that she was depending on him to make her dream a success, he also knew that he wouldn't always be there for her. Mizuki needed Sana to stop depending on him and stand on her own feet, so he told Sana that he would stop helping her. Sana didn't take this news well, and what they had already built up of her career started to crumble. Soon after, her career started failing, and she gave up on the dream that she had wanted so badly. This greatly hurt Mizuki who immediately blamed it on himself for abandoning Sana, and for destroying her dream. Ever since that day, he and Sana never talked to each other the way they used to, things were never the same between them.
Hime was one of the few people in a long time that he actually had interest in becoming friends with. They met when she stole his clothes in order to become a guy to protect her friend Tsukino. When Mizuki's friend Shuuma came in to check on him, he got so mad that someone would dare steal his friend's clothes. Shuuma made his fangirls bully Hime for a while but the bullying stopped when Mizuki kneed him in the stomach, saying that real idols don't attack girls. Even though the bullying stopped, Shuuma would still give Hime the evil eye. Around chapter 52, Mizuki realizes that he likes Hime although those feelings are not reciprocated.
- Mizuki knew about Hime disguising herself as Shiro from the beginning.