Appearing feminine in childhood spurred Rikyū Takiyama to pursue rigorous physical training and study judo in France, forging his determined personality. He is the son of Yoshie Takiyama, who is in a relationship with Seiji Yagashira, owner of the antique shop Kura. Rikyū deeply respects Kiyotaka Yagashira, regarding him as an older brother figure. This fuels his exacting standards toward Aoi Mashiro, whom he initially deems unworthy of Kiyotaka's attention.

Rikyū wields extensive antique knowledge, often displayed through trolling behavior toward Aoi at social events. His time abroad cultivated a sophisticated and subtly snarky demeanor. Later, he accompanies Aoi to New York, accepting an invitation from curator Sally Barrymore for a female curator training program. There, he supports Aoi through professional hurdles and personal conflicts about her relationship with Kiyotaka, evolving from antagonism toward collaboration. His character undergoes substantial evolution, engaging in significant cultural initiatives alongside main protagonists and transcending his initial role as a side character within the art world.