Kawai Yuko is just your average jr high school student. She is cute, funny, and should probably study more. Yuko is in her school band and plays the drum. She is also a good writer, having been nominated to write her class's skit twice. Yuko has a somewhat timid personality. She can be very insecure at times, worrying about her grades, her weight, her performance in the band, her friendship with Taka-chan, her lack of athletic ability, and her writing skills. However despite theis, Yuko has several friends, including: Taka-chan, Kitano-san, Hiroshi, Miyau-san, Maririn, and Rumiko. She lives with her mother, father, and her older sister

All of her life, she has lived next door to Hiroshi. Growing up, they were best friends, doing everything together from playing in the sandbox to walking to school together every morning. Yuko has always considered Hiroshi to be 'hers' in a close friend sort of way, but as the series begins, Yuko begins to see Hiroshi in a different light as she realizes how much he has grown up, and how much she has matured as well. Yuko is on the brink of womanhood. She is experiencing all sorts of new feelings, and notices that the world around her is changing along with her.

Mizuiro Jidai begins on the first day of the new school term. Yuko has just joined the band, and has to cope with the new challenges that face her, including tyrannical senpai, stern teachers, new relationships, and strain on old relationships. But Yuko somehow manages to handle it all with her bright smile and cheerful demeanor. Although she may have doubtsabout things, she is honest with herself and refuses to give up, always trying her best!

(Source: niko-niko.net)