Koyan Style is a series of countermeasures against Static Rook Bear-in-the-Hole tactics.
The common aim of all Koyan Style forms is, not to allow Static Rook to castle Four generals Bear-in-the-Hole, unlike Manabe Style.
The style name is derived from a nickname for Isao Nakata (7 dan), who is a professional shogi player using the style uniquely in current professional Shogi world.
Case 1. Against 33bishop + 64silver tactics
The keys are:
- Right knight is on 37.
- Pawn in 4th file is not on 45, but 46.
- Aims counterattack by using right knight
Black's central attack doesn't work on Figure 1 due to the deffence by right silver on 64.
(On the other hand, the central attack of Manabe Style can work because white's right silver is on 33. Please take a look at "Manabe Style" for comparison).
Instead, as soon as white starts attack, black counterattacks immediately.
Take a look at an example below: