Natsuki Takamizawa attends high school alongside her longtime childhood friend Tatsuya Asagiri, sharing both school and classroom. She works part-time at her family's adjacent restaurant, Trattoria Samon, assisting her brother Jin and father Samon with waitressing and support duties. Her culinary efforts consistently yield charred or inedible results—even salads—earning her the enduring nickname "Carbon Master" from family and peers.

Quick-tempered, Natsuki reacts explosively to teasing about her cooking failures, particularly from Jin or Tatsuya, often escalating into physical comedy like ejecting Jin through windows. Despite this volatility, she demonstrates fierce loyalty to Tatsuya, prioritizing his well-being and maintaining open communication even when suppressing her own feelings. She quickly befriends Feena Fam Earthlight, actively guiding her adaptation to Earth customs and integration into school life with classmate Midori Tōyama.

Living with father Samon, brother Jin, and mother Haruhi, her family dynamics feature frequent sibling clashes with Jin, balanced by her diligent restaurant work. Her role remains consistent across official adaptations as a supportive friend and comedic figure, defined by unwavering workplace dedication, protective instincts, and perpetually disastrous kitchen endeavors.