Cheerful Central Rook


In shogi, Cheerful Central Rook is a type of Central Rook opening in which the Central Rook player's bishop diagonal remains open.
This is a more aggressive strategy since the bishops may be exchanged at any time during the opening.
Cheerful Central Rook is played against a Static Rook opponent.

White variation

1. P-77 P-34, 2. P-26. Open bishop diagonals. Black plays Static Rook.
2....P-54. White pushes the central pawn, the signature move of Cheerful Central Rook.
3. P-25. Rook pawn advance.
3....R-52. Central Rook move.

Early pawn push

After White swings their rook to the central file, pushing the second file pawn by Black in order to trade the pawns off and get a pawn in hand is thought to be a mistake here since it will result in a position judged to be better for White.
After the pawn push and pawn trade off, since the bishop diagonals are both open, White will trade off the bishops and drop their bishop forking Black's rook and left silver.
If Black plays 7. Rx21+ aggressively capturing White's knight, White replies with 7....Bx88+ capturing Black's silver and aiming to bring the promoted bishop back to the 22 square in order to capture Black's promoted rook.
This continuation is believed to be better for White.
In case Black retreats the rook with 7. R-28 after 6....B*33, White can play the move 7....P*26 aiming for P-27+ to push Black's rook off the second file.

Castling

Gote usually aims for an Incomplete Mino castle:
However, there is always the option of a Bear-in-the-hole castle as well.

Countermeasures

Maruyama Vaccine

One of the most popular countermeasures against Cheerful Central Rook is the so-called Maruyama Vaccine. Tadahisa Maruyama started playing it by 2002, and it received that name thanks to the actual Maruyama vaccine, a vaccine developed in Japan in the 1970s against some types of cancer.
In the opening, before gote can move P-55, sente will go for a bishop exchange with 4. Bx22, Sx22, with the aim of gaining a bishop in hand and turning the game into a slow one. In reaction to this move, the strategy developed so that the Ranging Rook side would switch from a Mino castle to an Opposing Rook.

The New Maruyama Vaccine

Once the position in the Maruyama vaccine's diagram was arrived at, sente's king would castle at 5. K-68. However, gote would reply then by dropping the bishop with...B*33, from which sente would go with 6. N-77, and gote would push a pawn to...P-74 aiming at the head of the knight, and dropping a bishop at 7. B*88 would be pointless following...P-55. To avoid this situation, then, from the previous diagram the king won't move to 5. K-68, but instead the silver would move to 5. S-78, a move that is called the New Maruyama Vaccine. By moving the silver there, sente will be fully prepared for gote's bishop drop at 33.

5. P-96

From the New Maruyama Vaccine diagram, the game will go next with 5....K-62, 6. S-48, P-55, and a bishop drop at 7. B*65, and from there...G-32, 8. Bx83+, P-56, 9 +Bx56, Rx56, 10. Px56, and gote will have the advantage following...B*88. Yasumitsu Satō developed a new move to prevent this situation, where instead of 5. S-78, the pawn is pushed with 5. P-96.
Following 5. P-96, if gote goes with...P-9d sente will switch over to the New Maruyama Vaccine with 6. S-78. If instead gote goes ahead and pushes the central pawn with...P-55, then 7. B*65, G-32, 8. Bx83+, P-56, 9. Px56, B*88, and with 10. L-97 sente is in a good position. This move became popular after Satō defeated Yoshiharu Habu in an official game using this strategy in July 2005.