In or around 1855, he started using his artist appellation of Kunichika TOYOHARA for his signature, which combined the name of his first mentor, Chikanobu TOYOHARA, and Toyo-no-kuni.
安政2年(1855)頃より、最初の師である豊原周信と豊国の名前を合わせた画名である豊原国周と署名するようになる。