|Relatives, etc.||Haruki Tachikawa (Brother)|
|Anime debut||Episode 1|
|Manga debut||Chapter 21|
|English Voice||Terri Doty|
Yuko is an average-sized teenage girl with shoulder-length brown hair that has bangs hanging over her eyebrows, brown eyes light-green square-rimmed glasses and a warm expression.
She is often seen wearing her school uniform.
Yuko is a kind girl who cares about her friends as seen when she wanted Shinichi Izumi and Satomi Murano to patch things up. She enjoys teasing Satomi about her crush on Shinichi. Though she may become easily infatuated, as she quickly became attracted and started drawing pictures of Hideo Shimada. She even tried to talk him out of killing people to no avail.
She is clever enough to plan around Hideo's abilities in case he turned out hostile, discarding cutting or crushing tools in favor of a bottle of chemicals for her self-defense.
Yuko initially has a crush on Hideo, then while watching him she sees him reform a large dent in his head from being hit by a baseball. Due to her brother's line of work as a police sketch artist, she is peripherally aware of parasites and begins stalking Hideo. After witnessing him morphing his face to entice humans, she later confronts him alone at school. When he tries to attack her she throws paint thinner into his open head cavity. She manages to escape him by leaving through a window and jumping into a tree. Damaged by the paint thinner and unable to change his head back to normal, his head is stuck in attack mode and he rampages through the school, murdering 17 people before Shinichi stops him.
Shinichi, Satomi and Akiho Suzuki later check up on Yuko at the hospital.
- The name Yuko means "abundant, rich, plentiful, fertile" (裕) (yu) and "child" (子) (ko).
- Yuko's surname Tachikawa means "standing" (立) (tachi) and "river, stream" (川) (kawa).
- The Parasyte -the maxim- anime series gave Yuko a more prominent role in the series, introducing her much earlier and having her appear throughout the series.
- Yuko is the only full-blooded human in the series to survive direct conflict with a parasite.