Tamaki Kitakouji is Benio Hanamura's close friend. She radiates traditional femininity and beauty, contrasting Benio's tomboyish nature, yet both share strong convictions about women's rights and reject confining gender roles. They actively engage with the era's feminist movement, inspired by publications like Raicho Hiratsuka's Seito magazine. Tamaki explicitly invokes its manifesto: "In the beginning, woman was the sun. Now she is the moon. We must become a new woman."

Tamaki harbors romantic feelings for Shinobu Ijuin, the army lieutenant arranged to marry Benio. Upon learning of the engagement, she places her friendship and Benio's potential happiness above her own heart, encouraging Benio to consider the marriage despite Benio's objections to arranged unions. Tamaki handles this complexity with emotional maturity.

Later, Tamaki forms a relationship with military officer Shingo Onijima. Asserting her agency consistent with her beliefs, she chooses to follow him to Manchuria, prioritizing love and personal commitment over societal expectations. This significant decision reflects her developed willingness to embrace challenging paths for her convictions.

Her character development includes a nuanced view of adulthood. During the Tanabata festival, she expresses nostalgia for youth's boundless freedom to Benio, contrasting it with adult responsibilities and sacrifices, recalling when they "ate boundless dreams and hopes. We were as free as birds." Benio responds that even birds need branches to rest on, symbolizing acceptance of necessary compromises without abandoning ideals. This highlights Tamaki's reflective nature and evolving perspective on independence versus duty.

Her foundational friendship with Benio endures, marked by mutual support and an absence of rivalry despite shared romantic interests. She also maintains a friendship with Benio's close companion, Ranmaru Fujieda.