Kojirou Kageyama (影山小次郎) is Eiichiro Maruo's friend at Oosugi High School, and is one of the first characters to appear in the manga. He attends most of Ei-Chan's tennis matches and admires Natsu Takasaki, the school idol.
Kageyama has a large triangular nose and is often seen wearing a polo shirt. He has brown hair and a spiky hairstyle.
Kageyama is one of Eiichiro's closest friends, the two spending a lot of time together with him even helping Eiichiro with his tennis practice. He is not as studious as his friend and frequently depends on his notes in order to get by in class. Nonetheless, he is a good friend and is incredibly supportive of Eiichiro's goal to become a pro tennis player, often showing up to his matches to cheer him on and even sticking up for him when other students talked trash about him behind his back.
- Does not like tomato