Kaneyama (金山剛 Kaneyama Tsuyoshi) or Kain in Zatch Bell and Gash Bell Golden, is Kiyo's friend who was once largely known as the school bully. It was shortly after Kiyo changed his ways that so did Kain. Once he no longer became a bully, he soon became interested in finding "dinosaurs" or other rare monsters in an attempt to attain instant fame. He is still quite blunt in many ways and does largely rely on his brute strength to win in many endeavors.

Source: http://zatchbell.wikia.com/wiki/Kane