I have a complete set from 1st to 6th grade, but my child stopped reading them in 1st grade, so of course, they haven't read this book either. I'm selling it to someone at a low price. A children's book that lets you learn the wonders of science in a fun way. - Title: Why? How? 4th Grade - Price: 900 yen - Publisher: Takahashi Shoten Thank you for looking.