Multi-King Chess

This game is the same as usual western chess, except by the following rules:
1.- Every piece can promote to KING when that piece reaches the last rank, although it is not obligatory if the piece is not a Pawn. When a Pawn reaches the last rank, it MUST be promoted to King. A piece (not a Pawn) in the last rank can make a delayed promotion (to King), as in Shogi:  A promotion may be deferred to a later move, as long as this move begins inside the promotion zone (last rank). Where the move ends is of no relevance. 
2.- A Player wins the game if all enemy Kings are captured
3.- A King can move to a square in which it is in check

Setup

The same as in Chess

Pieces

The same as in chess

Rules

The same as in Chess, except by the rules explained before. There is not checkmate, you win if you capture all enemy Kings.

Notes

Thanks for David Paulowich, for the suggestion of Shogi promotion rule.