"Genius Drill to Cultivate Thinking Skills: Point Drawing to Excel at 3D Shapes: For All Elementary School Grades" Cognitive Engineering Price: ¥1000 No writing inside. It might be good to start with one a day from a young age, in a playful way. It also seems good for tackling in spare time, such as morning study. Recommended for children who are not good at spatial recognition or who have clumsy hands.