Chu shogi ( or Middle Shogi) is a strategy board game native to Japan. It is similar to modern shogi (sometimes called Japanese chess) in its rules and gameplay. Its name means "mid-sized shogi", from a time when there were three sizes of shogi variants that were regularly being played. Chu shogi seems to have been developed in the early 14th century as a derivative of dai shogi ('large shogi'). There are earlier references, but it is not clear that they refer to the game as we now know it.
With fewer pieces than dai shogi, the game is considered more exciting, and was still commonly played in Japan in 1928–1939, especially in the Keihanshin region. The game largely died out after World War II despite the advocacy of prominent shogi players such as and Ōyama Yasuharu (who played chu shogi when young and credited it with the development of his personal cautious and tenacious shogi style). In 1976, there were about 30–40 masters of the game. It has gained some adherents in the West, having been praised as "the best of all large chess games" by David Pritchard, and still maintains a society (the Chushogi Renmei, or Japanese Chu Shogi Association) and an online following in Japan.
The main reference work in English is the Middle Shogi Manual by George F. Hodges.
Rules of the game
Objective
The objective of the game is to capture the opponent's king and, if present, the prince, which counts as a second king. These two pieces are called "royal pieces", as the game is lost when a player is left without any of them. Alternatively, under the rules of the Japanese Chu Shogi Association, it suffices to capture all the opponent's other pieces, leaving a bare king or a bare prince, whereupon the player wins and the game ends early, provided that one's own king is not immediately bared or captured on the next move. Unlike standard shogi, pieces may not be dropped back into play after capture.
Gameplay
Two players alternate making a move, with Black moving first. (The pieces are not differentiated by color, but rather by facing of the pieces, with the "sharp" end pointed at the opponent; the traditional chess terms "Black" and "White" are only used to indicate who plays first, and to differentiate the sides during discussions of the game.) A move consists of moving a piece either to an empty square on the board or to a square occupied by an opposing piece, thus capturing that piece; and optionally of promoting the moving piece, if the move enters the promotion zone, or if it is a capture and any part of it is in the promotion zone.
Game equipment Two players, Black and White (or and ), play on a board ruled into a grid of 12 ranks (rows) and 12 files (columns), with a total of 144 squares. The squares are undifferentiated by marking or color, unlike a Western chess board.
Each player has a set of 46 pieces of 21 different types, and each piece has its name written on it in Japanese kanji. The writing is typically in black. On the reverse side of most pieces (i.e. except the king, queen, and lion) there are characters to indicate the piece's promoted rank, typically written in red. The pieces are wedge-shaped and their orientation indicates which player they belong to, as they point toward the opposing side. In all, the players must remember 28 moves for these pieces. The pieces are of slightly different sizes; from largest to smallest (most to least powerful) they are:
1 King 1 Queen (also referred to as a "running/rushing/free king", which is a direct translation of the Japanese name) 1 Lion 2 Dragon kings 2 Dragon horses 2 Rooks 2 Bishops 1 Kirin (sometimes called "Kylin", an anglicisation) 1 Phoenix 1 Drunk elephant 2 Blind tigers 2 Ferocious leopards 2 Gold generals 2 Silver generals 2 Copper generals 2 Vertical movers 2 Side movers 2 Reverse chariots 2 Lances 2 Go-betweens 12 Pawns
Listed below are the pieces of the game and, if they promote, the pieces they promote to. Names are rough translations that have become somewhat standardized in English. Pieces are listed alphabetically by their English name.
The promotions apply only to pieces that start out with the ranks in the left-most column. That is, pieces with these ranks written in black; promoted pieces with those same ranks written in red may not be promoted further. Pieces that only appear upon promotion, that is, names that only occur written in red, are marked with an asterisk. The king, queen, and lion do not promote.
+Pieces Piece name Kanji Romaji Abbrev. Promotion Short name Betza notation bishop(lit. 'angle mover') 3 dragon horse bishop B blind tiger 2 flying stag tiger FrlbW copper general side mover copper fKbW dragon horse 1 horned falcon horse BW dragon king soaring eagle dragon RF drunk elephant prince elephant FfrlW ferocious leopard bishop leopard FfbW *flying ox (promoted vertical mover) ox BfbR *flying stag (promoted blind tiger) stag fbRK *free boar (promoted side mover) boar BrlR go-between drunk elephant go-between fbW gold general 3 rook gold WfF *horned falcon (promoted dragon horse) falcon BrlbRf[avW]fD king (challenging)(lit. 'jade general') — king K king (reigning)(lit. 'king general') — king K kirin lion kirin FD lance(lit. 'incense chariot') 2 white horse lance fR lion — lion NAD[aK] pawn(lit. 'foot soldier') 2 gold general pawn fW phoenix queen phoenix WA *prince (promoted drunk elephant) prince K queen(lit. 'running king') 1 — queen Q reverse chariot 1 whale chariot fbR rook(lit. 'flying chariot') 飛車 3 dragon king rook R side mover free boar side mover WrlR silver general vertical mover silver FfW *soaring eagle (promoted dragon king) eagle RbBf[avF]fA vertical mover flying ox vertical mover WfbR *whale 2 (promoted reverse chariot) whale fRbQ *white horse 1 (promoted lance) white horse fQbR
1 The pronunciations of , and are irregular. The regular forms and are also seen. 2 The alternative pronunciations , , or , and are also sometimes seen. 3 Bishops, gold generals, and rooks arising from promotion (not the ones present initially) are sometimes given the alternate readings , , and respectively.
Below is a diagram showing the setup of the players' pieces. The board setup is symmetrical: the way one player sees their own pieces is the same way that the opposing player sees their pieces.
+Setup 12 11 10 9 8 7 6 5 4 3 2 1 L FL C S G DE K G S C FL L a RC B BT Ph Kr BT B RC b SM VM R DH DK Q Ln DK DH R VM SM c P P P P P P P P P P P P d GB GB e f g GB GB h P P P P P P P P P P P P i SM VM R DH DK Ln Q DK DH R VM SM j RC B BT Kr Ph BT B RC k L FL C S G K DE G S C FL L l
+ Setup legendAbbreviationName B B bishop BT T blind tiger C C copper general DE E drunk elephant DH H dragon horse DK D dragon king FL F ferocious leopardAbbreviationName G G gold general GB I go-between K K king Kr O kirin L L lance Ln N lion P P pawnAbbreviationName Ph X phoenix Q Q queen R R rook RC A reverse chariot S S silver general SM M side mover VM V vertical mover
In some contexts, one-letter abbreviations may be necessary. Those used in WinBoard are given in the second column of abbreviations. Promoted pieces are notated by a + in front of the symbol; thus a white horse is +L, and a promoted gold (now a rook) is +G.
Sometimes the kirin is abbreviated Ky (for kylin), and the queen FK (for free king).
Promotion
The promotion zone is the 'enemy camp', the farthest four ranks of the board, which are mostly occupied by the opposing player's pieces when the board is first set up. When a promotable piece enters the promotion zone from outside, or makes a capture starting within the promotion zone, it has the option of "promoting" to a more powerful rank. Promotion is not mandatory, and in some cases it may be beneficial to leave the piece unpromoted. (For example, the pawn, gold general, silver general, copper general, ferocious leopard, phoenix, kirin, vertical mover, side mover, and go-between all lose some of their powers upon promoting, so that there may be immediate tactical reasons for deferral, even though they all gain much more than they lose.) Promotion is permanent and promoted pieces may not revert to their original rank, nor promote a second time. If a piece is not promoted upon entering the promotion zone, then it may only promote by making a capture, or by exiting and reentering the zone. Pawns are an exception (see below).The Middle Shogi Manual allows pieces to regain their promotability after they move once without promoting. However, the Japanese Chu Shogi Association uses a different promotion rule, where a piece can only promote on a non-capture when it enters the zone. Once in the zone pieces can only promote on captures. There is strong evidence from historic mating problems that this has always been the rule in Japan.
Promotion is effected by turning the piece over after it moves, revealing the name of its promoted rank. Promoting a piece has the effect of changing how that piece moves. See below. For example, promoting a kirin turns it into a lion, and thereafter it behaves exactly like the original lion, even for the lion-trading rules. (Which can be a reason to defer promotion of a kirin.) A rook obtained by promoting a gold differs from an original rook, though, in that the latter can still promote (to dragon king), while the former cannot.
If a pawn reaches the furthest rank, it gets a second opportunity to promote on a non-capture. (This is because the pawn can never leave the zone, and there is a legitimate reason to defer its promotion: a pawn can stand between two protected lions without allowing either player to trade them, which is something a promoted pawn – a gold general – cannot do.) No such exception exists or is needed for lances (the only other piece with no backward moves) as there is never any reason to defer promotion of a lance in the first place: therefore, a lance that reaches the furthest rank without promoting becomes an immobile "dead piece" (). This last-rank promotion of pawns can likewise be declined, leaving the pawn as an immobile "dead piece". (Unlike for lances, this might still be done with reason, again because of the lion-trading rules.)
According to Okazaki Shimei, the go-between can likewise promote on the furthest rank on a non-capture. In the past, the Japanese Chu Shogi Association used this rule, but later repealed it because the go-between can go backwards. Some of the new rules given by Okazaki and not present in the Edo-period texts seem to be late innovations in the history of chu shogi from the Showa period.
Piece movement
An opposing piece is captured by displacement: That is, if a piece moves to a square occupied by an opposing piece, the opposing piece is displaced and removed from the board. A piece cannot move to a square occupied by a friendly piece, that is, by another piece controlled by the moving player.
Each piece on the game moves in a characteristic pattern. Pieces move either orthogonally (that is, forward, backward, left, or right, in the direction of one of the arms of a plus sign, +), or diagonally (in the direction of one of the arms of a multiplication sign, ×). The lion is the sole exception, in that it is not required to move in a straight line.
As stated earlier, this game is based on dai shogi and all of the pieces of this game can be found in dai shogi. The eight types of pieces that were removed were all rather weak and all promoted to gold generals. Furthermore, the larger board of dai shogi makes the slow-moving step movers even slower. All of this made for comparatively dull gameplay.
Many pieces are capable of several kinds of movement, with the type of movement most often depending on the direction in which they move. The movement categories are:
Step movers
Some pieces move only one square at a time. If a friendly piece occupies an adjacent square, the moving piece may not move in that direction; if an opposing piece is there, it may be displaced and captured.