Yuuko is a mysterious girl who Hiro first meets in a church on Christmas night. She always appears generally out of no where, and disappears just as quickly in various places throughout the story to talk with Hiro or other characters and give them advice; interestingly, Miyako already knows her. She could be considered the key character throughout the ef story.

She is a main character for the second series, part of which is focused around her connection to Himura.

Yuuko is a kind hearted person who hates being alone and puts on a brave face, even when upset or hurt.