The middle daughter of the Miyazawa family, Tsukino seems to be goofier and more laid back than her sisters. Tsukino tends to tease Kano, the youngest daughter.
Neither Tsukino nor Kano understands Yukino's quest for perfection. But they love her very much and are constantly begging her to play with them. (But Yukino usually can not because she has to study!)
In the manga, Tsukino became a talented tennis player. However, she had to retire from professional tennis due to injury, after which she became a reputable coach.