Explore 5 million Shogi mate situations in SFEN format

October 6, 2025 by shogishack

Recently, I became aware of a text file archive containing 5 million Shogi mate situations listed in SFEN format, and it is in the public domain.

This archive was released in December 2020, so I was nearly five years late to discover it. The author is Yaneurao-san, the person behind one of the strongest and most popular Shogi engines, Yaneuraou.

To read SFEN kifu, you typically need a desktop application that can interpret SFEN and display the Shogi board graphically. You’ll also likely need a script to extract individual SFEN lines from the text file and feed them into the application. The text file consists of 5 million lines of SFEN strings, divided into five separate files based on the number of moves required for checkmate (3, 5, 7, 9, and 11 moves).

To simplify the process, I’ve added a new page to our website under the “Tsume and Hisshi” section. This page randomly selects a line and displays it on a Shogi board. You can also manually select specific problems—for example, if you want to view the first five lines of the 7-move mate situations, this page allows you to do that.

I avoided using the term Tsume-Shogi (詰将棋) because these problems don’t strictly follow the rules of traditional tsume shogi, such as requiring a single solution and the use of all available pieces. Instead, these are real game situations where a checkmate exists.

No solutions are provided for these problems. If you have a desktop Shogi program that can solve mate problems, you can copy the position from this site (right-click and choose SFEN or BOD format—both should work) and let the program solve it.

The original file archive is linked in this Yaneurao-san’s blog post.

Enjoy!