Daigorō Kōya possesses spiky dark-brown hair with bangs hanging down the left side and brown eyes. His given name carries distinct meanings: "Dai" signifies "big" or "great," "Go" translates to "I" or "me," and "Rō" means "son." His surname, "Kōya," combines "kō," representing "happiness" or "good luck," with "ya," meaning "valley."

He addresses Otome Tsuzuki using the honorific suffix "-dono," a mark of his deep respect for her spirit of helping others. Following her Valentine's Day confession, he becomes engaged to Tamao Fujino.

Daigorō Kōya is characterized as a high school student, a martial artist, and a teenager.