Shogi opening sequences

Below is a list of the more common initial opening move sequences found in professional shogi games.
First move.
Out of the 64,046 recorded (mostly) professional games on Kyokumenpedia (局面ペヂィア) as of 2019 Jan 23 spanning the timeframe from the 1600s to 2018, 77.2% started with a bishop pawn opening (P-76) and 20.8% started with a rook pawn opening (P-26). The rook pawn push naturally leads to Static Rook openings; however, it is possible to play a Feint Ranging Rook as well. The bishop pawn push is more flexible and thus more ambiguous about the planned opening information given to White.
A less common first move (1.6% of Kyokumenpedia games) is the king's pawn (P-56). This move often suggests a Ranging Rook opening (Central Rook or Opposing Rook) for Black.
Other first moves are relatively rare and occur less than 0.5% of the time. For instance, the fourth most frequent move is the left edge pawn (P-96), but this only occurs less than 0.1% of the time.
Second move.
Just as the most common first moves are 1.P-76 and 1.P-26, the most common first move responses by White are also the rook pawn and bishop pawn pushes.
1. P-76.
Out of professional games with the bishop pawn push as the first move (1.P-76), 56.4% had White respond by advancing their bishop pawn (...P-34) and 42.5% responded by advancing their rook pawn (...P-84).
All other second moves (e.g. ...G-32) occur less than 1.1% of the time.
The ...G-32 choice prevents White from making a Boat castle, which is a standard castle used for a Static Rook position against a Ranging Rook opponent, since the Boat castle requires the king to the 32 square while the left gold remains on its starting 41 square. Thus, this move seems to invite Black to play a Ranging Rook position in order to exploit White's more limited piece development. Nonetheless, if Black chooses a Ranging Rook opening, White's gold on 32 can still be used to develop a Silver Crown castle or if Black plays a Bishop-Exchange Ranging Rook opening White can develop a Fortress castle in response with the gold in this position.
1.P-26.
Out of the rook pawn (1.P-26) first move games, 50.8% had a rook pawn advance as White's response and 48.7% had a bishop pawn response.
All other second moves (e.g. ...G-32) occur less than 0.5% of the time.
1.P-56.
Out of the central pawn (1.P-56) first move games, 65.5% had a bishop pawn advance as White's response, 30.2% had a rook pawn response, 2.5% have silver to 62, and 1.2% advance the central pawn.
All other second moves occur less than 0.6% of the time.
1.P-96.
Advancing the left edge pawn is an uncommon first move that like other more common first moves is usually followed by a bishop pawn (64.2%) or rook pawn (17.0%) push.
Less common responses include advancing either edge pawn.
First 2-move probabilities.
To state it in a different way, the probabilities of these first two-move sequences are shown below along with their log probability. In the adjacent diagrams are the six most common two-move positions.
These probabilities highlight how the most common first move from either side are the bishop and rook pawn pushes accounting for over 97% of all games.
Third move.
1.P-76 P-34.
Out of the 1.P-76 P-34 professional games, for the third move, Black:
All other third moves occur 1.7% of the time.
Playing 1.P-76 P-34 2.P-26 results in the same board position as a 1.P-26 P-34 2.P-76 sequence. (See: Transposition (chess).) This is the most commonly encountered 3-move sequence in shogi.
The 1.P-76 P-34 2.P-66 sequence suggests that Black may play a Ranging Rook opening (Opposing, Third File, or Fourth File).
However, Fortress or Snowroof are also possible.
The 1.P-76 P-34 2.P-75 sequence strongly suggests that Black will play an Ishida opening (Third File Ranging Rook).
Both the 1.P-76 P-34 2.P-96 and 1.P-76 P-34 2.P-1f sequences with the edge pawn push are relatively noncommittal initial moves by Black. Here, it is as if Black is asking White to determine which opening to play. (These moves also recall the shogi aphorism (将棋の格言 "shōgi no kakugen"): 手のない時には端歩を突け "te no nai toki wa hashifu o tsuke" "When there's no (good) move, push an edge pawn".)
1.P-76 P-34 2.P-96 can transpose to 1.P-96 P-34 2.P-76. However, 1.P-96 is an uncommon first move, and 1.P-76 P-34 2.P-96 is 38 times more likely than the transposition.
1.P-76 P-84.
Out of 1.P-76 P-84 games, common third moves for Black include:
All other third moves occur 0.5% of the time.
Playing 1.P-76 P-84 2.P-26 results in the same board position as the uncommon 1.P-26 P-84 2.P-76 sequence.
The 1.P-76 P-84 2.S-68 sequence suggests that Black might play a Fortress opening (Static Rook). Although Fortress is very common, the moves could also transition to other Static Rook openings like Bishop Exchange or Snowroof as well as to several Ranging Rook openings. This 3-move sequence is the second most common found in shogi.
1.P-76 G-32.
White's G-32 is an uncommon second move. Out of 1.P-76 G-32 games, common third moves for Black include:
All other third moves occur 20.6% of the time.
1.P-26 P-84.
Out of 1.P-26 P-84 games, common third moves for Black include:
Other third moves occur less 0.5% of the time.
Playing the uncommon "1.P-26 P-84 2.P-76" sequence results in the same board position as the more common "1.P-76 P-84 2.P-26" sequence.
1.P-26 P-34.
Out of 1.P-26 P-34 games, common third moves for Black include:
Other third moves occur 0.3% of the time.
Playing 1.P-26 P-34 2.P-76 transposes to the 1.P-76 P-34 2.P-26 sequence.
1.P-56 P-34.
Out of 1.P-56 P-34 games, the most common third moves for Black include:
All other third moves occur 1.4% of the time.
1.P-96 P-34.
Out of 1.P-96 P-34 games, the most common third moves for Black include:
First 3-move probabilities.
Below are the joint probabilities of these common 3 move sequences along with their log probability. The following table collapses different sequences that result in the same board position. The adjacent diagrams show the eight most common positions found in the game records.
Fourth move.
1.P-76 P-34 2.P-26 / 1.P-26 P-34 2.P-76.
Out of the 1.P-76 P-34 2.P-26 / 1.P-26 P-34 2.P-76 professional games, for the fourth move, White
Other fourth moves occur 6% of the time.
The "1.P-76 P-34 2.P-26 P-44" and "1.P-26 P-34 2.P-76 P-44" sequences suggest that White will play a Ranging Rook opening.
The "1.P-76 P-34 2.P-26 P-84" and "1.P-26 P-34 2.P-76 P-84" sequences suggest a Side Pawn Capture opening (Double Static Rook).
The "1.P-76 P-34 2.P-26 P-54" and "1.P-26 P-34 2.P-76 P-54" sequences suggest White will play a Central Rook opening (Ranging Rook).
The "1.P-76 P-34 2.P-26 G-32" and "1.P-26 P-34 2.P-76 G-32" sequences suggest White wants to play a Bishop Exchange opening (Double Static Rook).
1.P-76 P-34 2.P-66.
Out of 1.P-76 P-34 2.P-66 games, common fourth moves for White include:
Other fourth moves occur 19% of the time.
The first three moves already suggest that Black will play a Ranging Rook opening.
The "1.P-76 P-34 2.P-66 S-62" sequence suggests that White will play a Static Rook opening.
Both the "1.P-76 P-34 2.P-66 R-32" and "1.P-76 P-34 2.P-66 P-35" sequences suggest that White will also play a Ranging Rook opening (Double Ranging Rook), in particular Third File Rook.
1.P-76 P-34 2.P-75.
Out of 1.P-76 P-34 2.P-75 games, common fourth moves for White include:
Other fourth moves occur 35% of the time.
1.P-76 P-84 2.S-68.
Out of 1.P-76 P-84 2.S-68 games, White usually (99%) advances their bishop pawn (P-34).
Other fourth moves occur less than 0.5% of the time.
This 4-move "1.P-76 P-84 2.S-68 P-34" sequence will usually lead to a Fortress opening (just like the first 3 moves) with White threatening Black's bishop. However, it's still possible that Black could transition to a Bishop Exchange or Snowroof opening or a Ranging Rook openings like Central Rook or Opposing Rook. (Third File Rook or Fourth File Rook are less likely here as the silver is blocking the rook from moving to these files.)
1.P-76 P-84 2.P-26 / 1.P-26 P-84 2.P-76.
Out of 1.P-76 P-84 2.P-26 / 1.P-26 P-84 2.P-76 games, common fourth moves for White include:
The "1.P-76 P-84 2.P-26 P-34" sequence results in the same board position as the "1.P-76 P-34 2.P-26 P-84, 1.P-26 P-34 2.P-76 P-84," and "1.P-26 P-84 2.P-76 P-34" sequences – all of which suggest a Side Pawn Capture opening (Static Rook).
The "1.P-76 P-84 2.P-26 G-32" and "1.P-26 P-84 2.P-76 G-32" sequences suggest the possibility of a Bishop Exchange opening (Double Static Rook).
1.P-76 P-84 2.P-56.
Out of 1.P-76 P-84 2.P-56 games, common fourth moves for White include:
Other fourth moves occur 2% of the time.
1.P-76 P-84 2.S-78.
Out of 1.P-76 P-84 2.S-78 games, White usually (98% of the time) advances their bishop pawn (P-34).
Other fourth moves occur 2% of the time.
1.P-26 P-84 2.P-25.
Out of 1.P-26 P-84 2.P-25 games, White usually (96% of the time) further advances their rook pawn (P-85).
Other fourth moves occur 4% of the time.
This sequence suggests a Double Wing Attack opening (Static Rook). (It's possible that this could also transition to other Static Rook openings.)
1.P-26 P-34 2.P-25.
Out of 1.P-26 P-34 2.P-25 games, White usually (97% of the time) moves their bishop to the third file (B-33).
Other fourth moves occur 3% of the time.
First 4-move probabilities.
Below are the joint probabilities for these 4-move sequences.