Kouji Imai (今井コウジ, Imai Kouji)
Kouji is Ryōta's best friend. He is bold and quick witted as well as being knowledgeable as to what girls expect from guys and in his childhood, he was a habitual skirt flipper. He has black hair in the TV version and blond in the OVA. He often challenges Ryōta to several duels to see which of the two is better. He is afraid of Yuki cooking. His number on the class list is Kōji Imai is voiced by Yu Asakawa.