Overall, it's in good condition. This book, with mathematics at its core, is a self-study guide that aims to provide a comprehensive understanding of human culture, unbound by traditional subject classifications. Many fields, such as history, culture, mathematics, mechanics, atoms, and brain science, are explored with imaginary numbers as a central theme, written in a relaxed style that is accessible to junior high school students and up. The active use of kanji and calculators, among other things, provides a unique sense of fulfillment upon finishing the book. This book is a reprint published by our company, inheriting the same title from the original book (final edition: 32nd printing, March 2020) published by Tokai University Press in February 2000. Second edition of the first printing, March 20, 2022 (May 30, 2025) Price including tax: ¥4,730 Reduced from ¥4,500.