Morishita System.

Static rook, the Yagura · castles into Yagura · 森下システム Morishita shisutemu

The idea

The Morishita System turns the usual Yagura order round. Normally Black chooses an attack and White answers it; here Black castles first and waits to see what White does.

The bishop goes to 6h to clear the king’s path, and the right silver stays on 4h, so it can still go to 5g and 6f in the centre, to 4g after the pawn to 4f, or to 3g for a Silver-37. ja.wikipedia says Morishita Taku built it on Awaji Hitoshige’s and Aono Teruichi’s games, that he calls it a way of thinking rather than a strategy, and that for a while every Yagura was a Morishita System.

In this line Black jumps the knight to 3g, puts the rook on the 3rd file and then on the edge, and against White’s solid defence wins the edge pawn and attacks in the centre. The order after move 25, the system’s basic position, has one source.

How it goes together

Both sides’ moves are shown, because this opening is an agreement rather than a system: one player cannot reach it alone, so a one-sided list of moves would be a fiction.

The plan once you are set up

• Play the 24-move Yagura, then the bishop to 6h.
• Against White’s bishop on 6d, jump the knight to 3g rather than lifting the silver.
• Castle the king on 8h; push the edge pawn to 1f and put the rook on 3h.
• When White defends with the silver to 5c, build the lance on 1g, the pawn to 4f and the silver to 4g.
• Win the edge pawn, then push the pawns to 5e, 4e and 3e.

What to watch for

• White’s edge attack. ja.wikipedia says that because Black castles so early, White’s own Spearing the Sparrow on the 9th file became the system’s weak point, and for a time it disappeared. Fukaura Kōichi’s answer keeps the king on 7i and attacks in the centre with the silver on 4f and the pawn to 5e.
• White’s early Climbing Silver or 7th-file pawn trade. Against it, build the silver on 5g, the pawn to 6e and the silver to 6f.
• White’s edge pawn. If White does not answer the pawn to 1f, push to 1e and attack with the silver on 4f instead.
• The knight on 3g. With the rook on 1g it is guarded against White’s bishop.

What it is played against

White’s usual reply is the bishop out to 6d, then the Yagura with the king on 2b.

White can defend with the silver on 5c and back to 4b, as in this line, attack early with a Climbing Silver or a 7th-file pawn trade, or, as later players did, keep the king on 4a and attack Black’s castled king on the 9th file.