Renju VCF #4996508 (7-move VCF)
To move: Black — find the move that forces a win by fours
Winning line
J7 → I8 → J8 → J10 → J5 → J6 → I9 → H10 → L9 → K9 → K10 → M8
Why this move works
The answer is J7. A seven-move VCF that keeps White on the defensive with forcing fours (J7→I8→J8→J10→J5→J6→I9→H10→L9→K9).
The decisive K10 makes two winning points at once; White cannot cover both, and M8 makes five. What makes the whole line work is that every single move is a four.