lishogi.org/training/viAzl
The answer for this puzzle has 17 moves, but it is possible to check mate in 13 moves.
I’ve downvoted it. Also interested to know what the mate in 13 line is :)
If you try answering with ☗５四桂 it gives you as wrong answer. But if you start the engine with that play in the board it finds the solution below.
1.☗５四桂✗2.☖５四歩3.☗５三銀4.☖５三金5.☗５一銀6.☖５一金7.☗７一角8.☖６一玉9.☗５三角不成10.☖８一金11.☗７一金12.☖７一金13.☗７一龍