Sumire is a relatively tall girl, with long, reddish-brown hair that she keeps tied back into a ponytail with bangs hanging over her forehead and black eyes.
- Main article: Takagi
Sumire is a close friend of Takagi. During class introduction, she found out that Takagi shares the same hobby with her, which is going for walks, and she immediately became close friends with Takagi. She is usually seen with Takagi around the school, and is often her partner during activities while in gym class. Outside of school, they both like going for walks and hanging out with each other. As adults, Sumire and Takagi are still close friends and still hang out with each other.
- Sumire's surname Takagawa means "hawk, falcon" (鷹) (taka) and "river, stream" (川) (kawa/gawa).
- Prior to Episode 11 of Season 2, Sumire was simply named "Ponytail Girl (ポニーテールの子, ponītēru no ko)" in the endroll.
|Main||Takagi • Nishikata|
|Supporting||Mano • Nakai • Sanae • Yukari • Mina • Takao • Kimura • Hamaguchi • Houjou • Tanabe-sensei|
|Minor||Sumire Takagawa • Tunnel Fisherman • Tunnel Fishergirl • Tunnel Misc • Principal • Mano's Friend • Class 4-2 Unnamed Girl|