Micro shogi

Microshogi (五分摩訶将棋 "gofun maka shōgi" "5-minute (scarlet) poppy chess") is a modern variant of shogi (Japanese chess), with very different rules for promotion, and demotion. Kerry Handscomb of NOST gave it this English name. Although not confirmed, he credits its invention to the late Oyama Yasuharu, a top level shogi player. The game was invented before 1982.
Equipment.
Two players play on a board ruled into a grid of 5 ranks (rows) by 4 files (columns). The squares are undifferentiated by marking or color.
Each player has a set of 5 wedge-shaped pieces. The pieces are of slightly different sizes. From largest to smallest (or most to least powerful) they are:
Game rules.
The game is identical to standard shogi with the following exceptions.
Setup.
Each side places his pieces in the following positions, pointing toward the opponent. For more information see the ChessVariants.com page on micro shogi.
That is, the first rank is |S|G|B|K|.
Promotion.
Unlike standard shogi, microshogi has no promotion zone. Instead, a piece promotes when it captures, and promotion is mandatory. When a promoted piece captures, it "demotes"—that is, it is flipped back over to show its original unpromoted value.
Promotion values are entirely different from standard shogi:
Thus when a lance, tokin, rook, or knight makes a capture, it reverts to its former state.
A knight which reaches one of the two far ranks is trapped, as is a pawn which captures and thus promotes there. Likewise, a pawn that reaches the far rank is trapped, as is a knight which captures there. A lance is also trapped at the far rank, but can escape if it captures there and thus demotes to a silver. A silver which captures in the far rank and therefore promotes to a lance is trapped.
Any trapped piece may be captured and returned to play as part of the opposing army.
A tokin moves the same way as a golden general.
Drops.
Drops are similar to standard shogi, except that: