Despite his reputation as a genius, obtaining the "Jougen" spot when he took the Imperial Exams, Kōyū is notorious for having no sense of direction, constantly getting lost in the Imperial Palace in as little as thirty steps, and unable to get anywhere without the assistance of others (though at one point, Shūei notes that he doesn't seem to get lost while drunk). The acclaim he has received for his accomplishments often draws unwanted attention, which has developed into an aversion to most women after receiving a number of unwanted marriage proposals. Kōyū has a close relationship with Shūei Ran, though he loudly denies being the latter's friend. He loses his temper with very little prodding (often from Shūei, who constantly eggs him on) and gets tongue-tied speaking in official functions with large crowds.