This is apparently the first shogi-related question on this site! Yay!
Anyway, this is a mate-in-25 tsumeshogi. Sente (the player with the pieces pointing up) is to move and by an uninterrupted series of checks checkmate the opponent in 25 moves against best defence. (Shogi literature defines a move as one piece move or one drop by either player individually, so 25 moves means 13 moves by Sente and 12 by the opponent Gote alternating).
The position's SFEN is l1g6/kss6/2S6/1+BP3R2/9/9/9/6K2/9 b SNLrb3g3n2l17p 1. I created this tsumeshogi from a full game I saw on YouTube.
