Morishita Mayumi is a student living in the Shiawase apartment complex. Her defining trait is a shy demeanor. She nurses a romantic interest in fellow resident Haruka Tsuchiya. Due to her timid nature, she finds herself unable to express her feelings directly to him, often retreating into daydreams about their potential relationship instead. Her close friend Izumi provides support and actively works to facilitate interactions between Mayumi and Haruka.