The Three Pawns (歩三兵 fu sanbyō) handicap in shogi is used to teach novice players the vulnerability of bishops (角) and the threat of dropped pawns (歩).
Contents
White has only their king (王) on the board with no other pieces (like the Naked King 裸玉 handicap) and three pawns held in hand. Black has the usual setup of twenty pieces.
Opening
1. ... P*8f. As with all traditional handicap games, White has the first move. The standard first move is to drop a dangling pawn (垂れ歩) on the eighth file attacking the head of Black's bishop (角頭 kaku tō). White is threatening to promote this pawn to a tokin (と) on the their next move.
The test here is to see if Black can respond adequately to this threat. There are three ways to respond to avoid the loss of the bishop.
Silver response
2. S-7h. Moving the silver (銀) up to the h rank defends the 8g square rendering White's pawn attack futile.
2. ... Px8g+, 3. Sx8g. Although White can promote their pawn and capture Black's pawn (obtaining 3 pawns in hand again), Black can simply capture the promoted pawn.
Furthermore, Black's advanced silver can always retreat back to the 7h square if White threatens with another pawn drop (3. ... P*8f, 4. S-7h).
If White does drop another pawn and Black captures it (3. ... P*8f, 4. Sx8f), then Black's silver offers no protection for the bishop from White's subsequent pawn drop. However, now the 7i square is free for the bishop to retreat to. White's pawn on 8g is not a threat.
If Black plays from here on without major errors, they should become the victor.
Gold response
2. G-7h. Moving the gold (金) to defend the bishop's head is a standard move in many Double Static Rook (相居飛車) openings, such as Bishop Exchange, Double Wing Attack, or Side Pawn Capture. In the Three Pawns handicap, using the gold is slightly more complicated than using the silver (shown above).
2. ... Px8g+, 3. Gx8g. White's pawn promotes, and Black's gold recaptures.
3. ... P*8f. White can then strike with another dangling pawn.
4. Gx8f. Unlike the case with the silver defense, a gold cannot retreat and must move forward and capture the pawn.
4. ... P*8e. White will try another a drop with a striking pawn (叩きの歩). The hope is White can lure Black's gold forward.
5. G-8f. The correct response to the striking pawn is for the gold to retreat. After this, White's attack on the eighth file is exhausted.
If instead Black captures the striking pawn (5. Gx8e?), the gold will be positioned on the 8e square and no longer able to defend the bishop's head, the 8g square, where White can drop their last pawn (5. ... P*8g!) and capture Black's bishop on their next move (6. ... Px8h+!).
Similar comments apply to the gold moving sideways to either the left (5. G-9f?) or right (5. G-7f?).
Bishop diagonal
2. P-7f. Another possible but suboptimal move is to create an escape hatch for Black's bishop.
2. ... Px8g+, 3. B-3c+. Although White can promote their pawn, Black's bishop can escape to 3c and promote as well checking White's king.
After White resolves Black's check, White has a further chance to exchange pawns for more powerful pieces. For example, White can sacrifice a pawn (4. ... P*9h, 5. Lx9h) and then drop another pawn (5. ... P*8h) in order to attack both Black's lance (香) and knight (桂) allowing White to trade a pawn for a lance and possibly the other pawn for another piece.
Thus, although Black has saved one their most powerful pieces, opening up the bishop diagonal gives White more of an advantage compared with protecting the bishop's head with a silver or gold. Furthermore, the bishop's diagonal can always be opened after proper defense of the bishop's head.
Blunder
2. Px8f? Black reflexively capturing White's pawn on 8f is a blunder. Although this captures White's pawn, it does not remove the threat to Black's bishop as the bishop's head is still vulnerable.
2. ... P*8g! White can now drop a pawn directly on the bishop's head. At this point, Black has no way to prevent White from capturing their bishop and dramatically improving White's chances.
This pawn drop on the bishop's head is a tactic that can be applied to real even game openings such as the Double Wing Attack opening (相掛かり) if either Black or White does not appropriately defend their bishops' heads.