Nikumaru, meaning meatball in Japanese, is a seventeen-year-old student at Ninja High School, a special school for the training of ninja. He is short and chubby, but he possesses a super technique known as the "kamikaze", where he stirs up a whirlwind with his feet. The series introduces his many adventures and pranks as Nikumaru meets with his rivals both in and out of school.

• Saeko Shimazu
• Kenichi Ogata
• Norio Wakamoto