Sachiyo Usui, an eccentric manga artist dwelling in Moonlight Town, creates unsettling, highly detailed drawings notorious for unsettling the community. Her haunting artwork earns a reputation as distinctly creepy. Persistent writer's block plagues her, frequently impeding the manga production process; this recurring creative struggle forms a consistent thread in her character narrative across episodes.

Her profession actively fuels multiple episode plots, centering on her artistic process and difficulties. Specific installments like "The Dark Sachiyo Usui" and "Sachiyo Usui and the Light of Hope" delve into her creative endeavors, showcasing challenges and occasional breakthroughs. During these narratives, she interacts with other residents, often involving them in her pursuits or seeking inspiration from town events.

While primarily defined by her intense artistic identity, a nurturing side occasionally surfaces. She demonstrates responsibility for Ojarumaru's well-being in certain instances, exhibiting practical concern for his safety through direct actions.

Her presence remains a constant throughout the series, including the 19th season. She retains her core identity as a manga artist with distinctive artistic traits, maintaining her role and personality without significant alteration over time.