This is the Sigma Series "Kore de Wakaru Suugaku I+A" (Understanding Math I+A) for high school students, published by Bun'eido. It's a textbook, not a problem set. Brand new, unused. Due to storage, there's a slight crease on the label, but the inside is completely unused, so please rest assured. This book covers the basics to standard level of Math I+A, with detailed and easy-to-understand explanations and a clear writing style. 《Notes》 ✅ The actual product may have slight variations from the model photos. There are absolutely no issues with the product itself, so please understand. ✅ The texture and color may appear different from the actual product depending on your device, please understand. ✅ We will ship within 1-2 days. Shipping to Hokkaido, Okinawa, and remote islands requires an additional fee of 2000 yen. Please understand. ✅ We also accept comments, set sales, and price negotiations, so feel free to contact us! #SigmaSeries #HighSchoolMath #UniversityEntranceExam #Math #Bun'eido