Doraemon Study Manga, 6 books. Exploration World: Do You Know? The Secrets of Names Sleep and the Mysteries of Dreams Social Studies World: Let's Become Strong with Information The Secrets of Money Science World: The Wonders of Weather and Meteorology The Wonders of Electricity All are used items. "Do You Know? The Secrets of Names" has some stains. The others have no noticeable stains, I think. Please understand that this is a personal inspection, and I will sell them to those who agree. We also welcome combined purchases with other manga!