Megumi Amatsuka, known as Megu, is the middle child of the Amatsuka family and Mao Amatsuka's younger sister. Though younger, she stands taller than Mao. She has distinctive pink hair, usually tied in a bun secured with a blue ribbon, and pink eyes. Her typical attire is her school uniform.

As a dedicated member of the GJ Club, Megumi routinely prepares and serves tea to the other members. She also bakes cakes for club gatherings, occasionally sacrificing sleep to complete them on time. Her personality is consistently calm, quiet, and composed, remaining unfazed even during events that unsettle others, such as encountering spiders. She approaches games with intense seriousness and reacts strongly to comments about her weight, being sensitive about weighing 50 kilograms.

Megumi possesses traditional feminine skills, including knitting the club's costumes, and excels at domestic tasks like cleaning. Baking is a particular enjoyment, leading her to provide desserts during club activities. She is also an avid fan of the fictional series "Ore Man."

She frequently worries about her older sister Mao's shyness and social interactions. Megumi assists Mao with personal care, gently brushing her hair to prevent tangles or split ends, and expresses deep affection for both her sisters. Her interactions with the sole male club member, Kyōya Shinomiya, involve serving him tea and expressing gratitude for his presence; she maintains a uniquely polite and gentle demeanor towards him.

Megumi embodies a more nurturing and serene disposition compared to Mao's temperament. Her sensitivity about body image becomes noticeable in contrast to the club's newest member, Tamaki Kannazuki, who claims an immunity to weight gain despite frequent snacking. This difference sometimes creates tension between them.