She used to be close with Darcy, but their relationship soured significantly after they started playing on the same tennis team. Her values and personality differ from Darcy's. Marcy pretends to be a bright girl and takes great pride in being a tennis player and winning trophies. She is a workaholic who prioritizes matches over health and is a strict planner; she becomes extremely angry or cold if her career or plans go awry. Her true personality is blunt and cold. Surprisingly, she is quite a brat. In truth, she also misses her mother and suffers greatly when the angel and devil inside her clash, though she seems to ignore it lately.

She wants to be close with Marcy again, but in reality, she doesn't make a genuine effort and is always indifferent, rarely speaking to the point of near-silence. Naturally, she prioritizes health over matches. She is extremely lonely and misses her mother so much that she uses antidepressants like drugs. However, she is good at tennis. She is more mature than Marcy. She does laugh and cry occasionally, though these emotions are very rare. She has mental health issues. She seems proficient with computers, even creating portals on her own. Having been heavily socialized to the point of numbness, her eyes only widen slightly even when a serious crisis occurs.

Appears only as 'Coach' without a specific name. He is the director supervising Marcy and Darcy and doesn't care much about how they behave. He shows the typical shamelessness of someone exploiting children, asking if their arms are okay instead of asking if they are hurt. He believes as long as they play tennis well, nothing else matters.