Hifumi has a verbose manner of speaking, often going on long-winded tangents about his interests such as anime or fanfiction. He also has a tendency to casually make creepy or perverted comments in the middle of conversations, especially about or to women. He can also be oblivious to how others perceive him, as shown when Toko says he smells like a "big fat ugly donkey" — he couldn't tell if that was an insult or a compliment. However, he also displays some intelligence.