Monochromatic Pawn
The Monochromatic Pawn is color bound, and so can only move and capture diagonally forward. If it is both the Monochromatic Pawns first move and the Monochromatic Pawn is not capturing anything it can move one or two squares diagonally forward, otherwise the Monochromatic Pawn can only move one square diagonally forward. When the Monochromatic Pawn gets to the end of the board it promotes, but it is only allowed to promote to a color bound piece in order to keep itself color bound.
What is Tenjiku Shogi?
https://en.wikipedia.org/wiki/Tenjiku_shogi