Book excerpt: The book presents the main features of the Wasan tradition, which is the indigenous mathematics that developed in Japan during the Edo period. (1600-1868). It begins with a description of the first mathematical textbooks published in the 17th century, then shifts to the work of the two leading mathematicians of this tradition, Seki Takakazu and Takebe Katahiro. The book provides substantial information on the historical and intellectual context, the role played by the Chinese mathematical treatises introduced at the late 16th century, and an analysis of Seki’s and Takebe’s contribution to the development of algebra and calculus in Japan.