Kō Sawatari, born August 31, 2001, is the younger brother of protagonist Fū Sawatari. He resides with his mother Tamae, grandmother, and sister above Cafe Tamayura, where he serves dishes. His notably effeminate appearance frequently causes others to mistake him for a girl upon first meeting, leading directly to Norie Okazaki's initial confusion and subsequent persistent infatuation.

As an elementary school student, Kō displays a cheerful, friendly disposition. He generally accepts Norie's enthusiastic attention, maintaining a calm demeanor despite her frequent advances. Classmate Komachi Shinoda also develops feelings for him, resulting in a recurring comedic rivalry between her and Norie over his affection.

Kō plays a significant role in his sister's emotional recovery after their father's death. He rediscovered old family photographs taken by their father, inspiring Fū to resume using his camera and pursue photography again—a pivotal act for her healing. His supportive nature includes accompanying Fū to events like photographer Riho Shihomi's exhibition.

Throughout the series, Kō remains a grounding family presence. His relationship with Fū is warm and trusting, reflecting shared history and mutual support. During Fū's later high school years, depicted in the graduation film series, Kō continues as part of her daily life as she navigates future uncertainties.