Atama no Taisou (Japanese: 頭の体操, lit. Head Gymnastics) is a puzzle collecting books series that was released by Kobunsha, and the author is Akira Tago. As of 2010, there were 23 regular volumes with an e-book volume released.
The first volume was published in 1966 and sold more than 2.5 million. The series has sold 12 million copies and become a best-seller.
References
Atama no Taisou Wikipedia(Text) CC BY-SA