Due to the shackle on her left arm, her suspicious double buns with bun covers, and her title implying the existence of horns, there is rampant speculation among fans that Kasen is an oni, specifically Ibaraki Douji, one of the Big Four. Some of Kasen's actions, such as her avoidance of Ibuki Suika, also contribute to the speculation.
She is often accompanied by her pets: Koutei the dragon, Kume the giant eagle, Kanda the young eagle, Mukou the raijuu, and Houso the tiger.
Since both characters are hermits, Kasen is often associated with Kaku Seiga, though usually on an antagonistic basis since Seiga is a "wicked hermit".
Wild and Horned Hermit 35 revealed she is one of the Sages of Gensokyo alongside Yukari.
Wild and Horned Hermit 49 would not only introduce her severed arm given semi-physical form, Ibaraki Douji's Arm, but Kasen herself would become one with her arm and fully become an oni once more, revealing herself to be one of the Big Four, Ibaraki Douji. Also associated with Miyako Yoshika as the real Miyako No Yoshika wrote poems that Douji supposedly liked.
