Hisshi

In shogi, hisshi or brinkmate (必至 "desperation, inevitability" or 必死 "sure kill") is the situation in which an unavoidable checkmate sequence (詰め tsume) will be created by the player's next move.

Hisshi differs from the situation in which a checkmate sequence is only being threatened to be created in the next move but is still avoidable if the opponent defends correctly. This situation is known as 詰めろ tsumero or threatmate ("threatened mate"). Thus, hisshi is an indefensible tsumero.

The only way to prevent a loss from hisshi is for a player to not give their opponent a chance to actually create the tsume checkmate sequence and instead initiate their own tsume (with constant checks) before their opponent's move. (Thus, a good exemplification of the saying the best defense is a good offense.)

Although the terms brinkmate and threatmate were coined to translate the Japanese terms, the concepts can equally be applied to western chess and other chess-like games. (See: §Western chess below.)

Shogi

Example

Fig. 1. (pre-)Hisshi problem △ pieces in hand: all the rest 9 8 7 6 5 4 3 2 1   香 桂               a                   b 王 銀 歩             c 歩 歩               d                   e                   f                   g                   h                   i ▲ pieces in hand: 金

Fig. 2. Hisshi (answer) △ pieces in hand: all the rest 9 8 7 6 5 4 3 2 1   香 桂               a                   b 王 歩             c 歩 歩 全             d                   e                   f                   g                   h                   i ▲ pieces in hand: 金 S-7d+

Figure 1 shows a classic hisshi problem.^[1] Here, Black does not have a way to immediately checkmate White's king. However, Black can create hisshi by moving and promoting their silver to the 7d square (Fig. 2).

Fig. 3. White's Response #1: Capture △ pieces in hand: all the rest 9 8 7 6 5 4 3 2 1   香 桂               a                   b 王               c 歩 歩 歩             d                   e                   f                   g                   h                   i ▲ pieces in hand: 金 ... Px7d

Fig. 4. Tsume #1 (1 move) △ pieces in hand: all the rest 9 8 7 6 5 4 3 2 1   香 桂               a                   b 王 金               c 歩 歩 歩             d                   e                   f                   g                   h                   i ▲ pieces in hand: – G*3c

From this position, Black is threatening to drop their gold in hand to 8c in their next move to render an immediate mate.

Even if White were to try to remove Black's promoted silver with ...Px7d (Fig. 3), this does nothing to prevent the simple mate in one with G*8c (Fig. 4).

White has two possible ways to attempt to defend against this threat.

But, since this is hisshi and not merely tsumero, all attempts are futile as explained below.

If White tries to defend the 8c square by dropping a defender (such as a gold) to 8b (Fig. 5), then Black can initiate a 3-move mating sequence starting from G*8c (Fig. 6).

Subsequent moves are ...Gx8c, +Sx8c (tsumi).

Fig. 7. White's Response #3: Escape △ pieces in hand: all the rest 9 8 7 6 5 4 3 2 1   香 桂               a   王               b   歩             c 歩 歩 全             d                   e                   f                   g                   h                   i ▲ pieces in hand: 金 ... K-8b

Fig. 8. Tsume #3 (3 moves) △ pieces in hand: all the rest 9 8 7 6 5 4 3 2 1   香 桂               a   王               b   全 歩             c 歩 歩             d                   e                   f                   g                   h                   i ▲ pieces in hand: 金 +S-8c

If White's king tries to flee to the 8b square (Fig. 7), then Black can initiate a 3-move mating sequence starting from +S-8c (Fig. 8).

Subsequent moves are ...K-7a, G*7b (tsumi).

Alternately, instead of +S-8c, Black could move P-8c+, then K-7a, G*7b (tsumi).

Hisshi vs tsumero

The first adjacent diagram has an example of tsumero that is not hisshi. It is now White's turn to play. Although Black has a possible checkmate in their next move by dropping their gold to the 8b square, White can defend against this by dropping a gold to 7a defending the 8b square. With this move, White has removed the threat of Black's tsumero. If Black dropped their gold to 8b now, then White would simply capture it and attack Black's other gold (that is, ...G*7a, G*8b Gx8b).

In the second diagram, there is an additional pawn positioned on 7c. This difference gives Black hisshi (as well as tsumero). Any defense attempt by White will fail. White's ...G*7a will be met with G*7b Gx7b, Px7b+ (tsumi). There are similar mate sequences if White tries ...R*3b, ...G*8b, etc. Similarly, it is impossible for White's king to escape with ...K-7a.

Silver on the belly tactic

Silver on the belly (腹銀 haragin "belly-silver") is a basic brinkmate tactic in shogi. This tactic positions a silver (by moving there or by dropping) directly on either side of the opponent's king. The adjacent diagram shows a typical silver on the belly brinkmate. Here the silver is placed on the 8b square. The one-move mates +R-8a, +Rx9a, S-8a=, or Sx9a+ are unstoppable. For instance, if White moves P-9d, then +Rx9a is mate, and if White moves N*8a, then the silver or dragon taking 8a are mates.

That leaves the longest (7-move) mate sequence in which the king attempts a futile escape starting with P-8d. Subsequently, the dragon chases. Thus, 2. +Rx9a K-8c, 3. +Rx9c K-7b, 4. +R-7c K-6a, 5. +R-7a is a mate.

Western chess

Brinkmates (hisshi) and threatmates (tsumero) are also found in western chess.

Position after Qh6!!

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Black has no way to prevent Qg7#. This position is brinkmate (hisshi).

Position after Qf7!!

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Despite the fact that no matter what move is played, there will be a mate, this is not a brinkmate because this is not even a threatmate (tsumero). However, black is in zugzwang and must move either his knight allowing Qxh7# or his h-pawn allowing Ng6#.

Position after ...Qa3?

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

White has no way to avoid ...Qb2#, but white can play 1. Ng6+ hxg6 2. hxg6+ Bh7 3. Rxh7+ Kg8 4. Rh8+ Kxh8 5. Rh1+ Kg8 6. Rh8+ Kxh8 7. Qh1+ Kg8 8. Qh7+ Kf8 9. Qh8#

Position after Qh6

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

This is a brinkmate, but black has Qf1+ and Qf2+.

Position after Qh6

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

This is a tsumero but not a hisshi. ...Bf8 stops Qg7#.

Position after Qh6!!

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

This is a tsumero and a hisshi. Black cannot play ...Bf8 to defend Qg7# because his rook is there. ...Bd4 doesn't help.

Brinkmate in 2

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

1. Qg5! g6 2. Qh6!! brinkmate.

See also

• Tsumeshogi
• Checkmate

References

Bibliography

• Fairbairn, John (1986). Shogi for beginners (2nd ed.). Ishi Press. ISBN 978-4-8718-720-10. 
• Kitao, Madoka (2014). Ending attack at a glance. Translated by Kawasaki, Tomohide. Nekomado. ISBN 978-4-9052-2513-3. 

External links

• Shogi Shack:
  • ABC of Hisshi
  • Simple Hisshi · 1-move and 3-move hisshi problems
• HIDETCHI's YouTube video: How to play Shogi (将棋): Lesson #31: Threatmate and Brinkmate