Serina Shinjo

She is also Masato's childhood friend and Haruna's younger sister. Unlike her brainy older sister, she is not very smart, but she is the type who follows the leader. Her beautiful body, which can be seen even through clothes, is popular in a different way from her sister. She is not as sneaky as her sister, but she is assertive towards Masato, who she clearly looks down on. She is also interested in making easy money, so she won't tutor him.