In shogi, the Ureshino (嬉野流 ureshino-ryū) opening is a newer aggressive Static Rook opening characterized by moving the right silver to the sixth file and then pulling back the bishop to the silver's start position.
[1] It has an element of surprise as the move sequences are nonstandard and not found in professional play.
The opening is named after amateur player Hiroaki Ureshino (嬉野宏明) who invented it.
For White's next move, it is most likely that they will open their bishop's diagonal by advancing their third file pawn.
[a] It is also possible for White to push their rook pawn (1...P-84) instead of opening the bishop diagonal.
Thus, the bishop is pulled back to the seventh file aiming at the 57 square, which Black will open with a future P-56 pawn push.
The point here is to delay this possibility to encourage White to pull their rook back off the rank 6 so that Black can keep their fifth pawn on 56.
After 4.S-48, White's Static Rook strategy has two major options: either (i) to immediately make a pawn exchange on the eighth file to get a pawn in hand or (ii) to delay making this exchange for faster development.
Both options can be used with a Climbing Silver attack, which will be tempting for White since Black has only the most minimal of defenses on their left side (only a gold on 78 missing a bishop on 88 and an uncastled king).
The advantage of second option is that developing a Climbing Silver attack without the initial pawn exchange results in a faster attack since the pawn exchange requires loss of tempo.
Therefore, the Ureshino player prefers the first case when White makes the early rook pawn exchange.
It is common for White to initiate the pawn exchange on their rook's file when possible.
Due to this tempo loss, if Black is strictly playing the Ureshino strategy, White can attack with Climbing Silver faster if White does not make this rook pawn exchange first.
But, White also has another option of simply developing other pieces for defense as their rook can remain on the 86 square since it is not under attack (see §6...S-42 further below).
White retreats their rook back to its start position preparing for a Primitive Climbing Silver attack.
White aims for a Primitive Climbing Silver attack on the eighth file eschewing defense development.
White must defend the 24 square to prevent Black from trading the second file pawns.
White moves their silver to the middle rank aiming for the 86 square in order to support a pawn drop on 87.
Instead of immediately going into a Climbing Silver attack, White may choose to build a Fortress defense starting with developing their left silver in order to Black's next rook pawn push with S-33.
A logical choice is S-42, which will be part of an incomplete Snowroof castle with their left gold on 32 and the bishop on 33.
(Another possibility would be a Fortress castle with the silver eventually on 33, the gold on 32, and the bishop remaining on 22 where it can be pulled back to 31.)
The tradeoff with getting a pawn 'for free' is that White have the typical tempo loss associated with taking a side pawn gambit: it requires an extra tempo to move the rook back to the eighth file (cf.
It is this rook pullback that costs one tempo for White resulting in a slower attack.
Black advances their rook pawn while White castles their king toward the eighth file.
Black pushes the third file pawn in preparation for Diagonal Climbing Silver.
Black immediately starts their Diagonal Climbing Silver by attacking the third file.
In contrast to the traditional use of a Static Rook Boat castle against Third File Rook[c], Black does not fear White's pawn push on the fourth file (P-45) to attack their silver on 46 since in the Ureshino opening Black's bishop diagonal is not open and White cannot trade the bishops off the board for a counterattack to their advantage.
This pawn drop is forced to prevent White's bishop from capturing Black's rook.
S-37), White will simply attack the silver with pawn drops and pushes in order to capture it: 14...P*36, 15.
Thus, the current theory is that a Diagonal Climbing Silver Rapid Attack with a Boat castle formation (with S-46) is inadequate against Central Rook.