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I also agree that Tenjiku Shogi's promotion rule should be the same as that of Chu Shogi. But for Lions, Horned Falcons, and Soaring Eagles, these rules are a bit vague. Of course, Chu Shogi is of no use to us here since these pieces don't promote in that game. So I decided to follow H. G. Muller's interpretation, which makes the most sense in my opinion.

In his interpretation of the first rule, the piece must start its move outside the promotion zone and end its move inside it. If a piece moves multiple times, the intermediate square(s) would not be considered since the piece did not start or end its move there.

In his interpretation of the second rule, the piece must start in the promotion zone and capture something with its move. It's well established at this point that a capture is any move that removes an enemy piece from the board. This presumably means that if a piece makes a capture on its first step and a non-capture on its second, this would still count as a capture since the piece captured something.

Now let's consider the effects of this interpretation on these scenarios suggested by dax00:

• A Lion that enters the promotion zone on a non-capture and then exits the zone while capturing a piece should be able to promote
• An unpromoted piece that starts in the promotion zone, captures a piece in the promotion zone on its first step, and makes a non-capture on its second step should not be allowed to promote

The first scenario is flawed because it breaks both rules. The Lion did not enter the promotion zone - both its starting square and its destination square are outside of it. This makes the capture on the Lion's second step meaningless.

The second scenario is flawed because it meets the criteria in the second rule. The piece started its move inside the promotion zone and captured something on the way to its destination, so it has the option of promoting on that turn.