Hirono Shimizu was a member of the gang headed by Mitsuko Souma. She was often referred to as 'Hiro' by her classmates, even though they were not her friends. She had been involved with both recreational drugs, prostitution, shoplifting, and bullying other classmates. Although she was considered a "bad girl", Hirono was quite opposed to the idea of having to kill unless it was in self-defense. Hirono also never saw most of her actions as harmful, and it does not seem that she was pressured into committing crimes by Mitsuko, like Yoshimi Yahagi was. Her delinquent activities have given her a clearly advanced level of maturity and perception.