The series has been made into a book form that has sold over 6 million copies in Japan . Akamatsu received the Kodansha Manga Award for shÅ nen in 2001 for this series . The series appeared in Weekly Shonen Magazine and has been collected in eleven volumes ( with fourteen volumes in total ) , which have sold over 6 million copies in Japan , and received the Kodansha Manga Award for shÅ nen in 2001 .