Usagi is a school girl who lives in 20th Century Tokyo. At the start of the series, she is 14 years old and she is in her second year of middle school. Near the end of the series, she is 16 years old and she goes to high school.

Initially, Usagi was shown to not view life with a great deal of seriousness, apart of being somewhat immature and described herself as a bit of a "crybaby". Lively and ease-going, she usually goofs off and neglects her schoolwork to play video games or spend time with her friends.

Despite all this, Usagi acts friendly towards many people and tends to help others out with their problems, being a compassive, empathic and unexpectedly observant person. As the series progresses, Usagi slowly matures and learns how to make decisions for herself as well.