21. a piece already in the way, by the soldier

Helpmates in xiangqi

4 moves

Black moves first and both sides cooperate: Black, Red, Black, Red, and Red's second move mates. Black has 22 legal first moves and exactly one of them works. 17 pieces, Black 39.5 to Red 4 in material, mate by the soldier. Themes: a piece already in the way, a piece returns wher…