The main 36 volumes of the series have been complete in January 2020. This series has exceeded 5.2 million copies in total and is an enlarged and revised version of the “10 Minutes to Complete Reading” series, which has been supported by many readers since its publication in 2005. The contents have been reviewed in accordance with the current interests of children, and more pages have been added to foster the "ability to think independently" corresponding to the New Courses of Study. The cover painting was created by Studio Ponoc, an animation film production company founded by former Studio Ghibli's Yoshiaki Nishimura.