Rena Isayama (伊佐山玲奈 Isayama Rena) is a friend of Yumiko Minamino and a notorious troublemaker.
Growing up in a poor family environment, Rena started her misconduct when she was a junior high school student. The only family member she is kind too is her grandmother, who has been taking care of her for a long time. She has been close to Mai Sawano, the daughter of Kinuyo Sawano the owner of Hokuhoku Lunches, for years and recently made her a member of her gang. Though she’s only 16 years old, she is dangerous, and she conceals a sharp razor blade in the sleeve of her school uniform.
- Rena's zodiac sign is Pisces and she has a A blood type.