The haikara of the title is Benio Hanamura, a 17-year-old schoolgirl in Tokyo circa 1920 (during the Taishou era). Benio lost her mother when she was very young and has been raised by her father, a high-ranking official in the Japanese army. As a result, she has grown into a tomboy—contrary to traditional Japanese notions of femininity, she studies kendo, drinks sake, dresses in often outlandish-looking Western fashions instead of the traditional kimono, and isn't as interested in housewife duties as she is in literature. She also rejects the idea of arranged marriages and believes in a woman's right to a career and to marry for love. Benio's best friends are the beautiful Tamaki, who is much more feminine than Benio but equally interested in women's rights, and Ranmaru, a young man who was raised to play female roles in the kabuki theater and as a result has acquired very effeminate mannerisms.

(Source: Wikipedia)