Snowroof

In shogi, Snowroof or Snow Roof Fortress (雁木 gangi, lit.

It is named after the covered sidewalks (雁木造) connected to buildings in Niigata Prefecture.

Originating in the Edo period, the opening had been a less common one after World War II although it was popular in the prewar era.

Naitō (1981) notes that the Snowroof was once very popular and had a reputation for being very difficult for a Fortress opponent to defeat.

Hisao Hirotsu (Black) used a Snowroof castle against Osamu Katsuura's Fortress position in a 1977 Kisei tournament game on January 11.

Yoshiharu Habu (White) used a Snowroof castle against Masayuki Toyoshima's Fortress position in a 2014 Asahi Open tournament on February 2.

Thus, taking this Snowroof to Silver Fortress approach will probably cause a player to have a strictly defensive position.

Kinjirō Kimi (木見金治郎) vs Chōtarō Hanada (花田長太郎)[5] Double Snowroof position Hanada (White) develops his Snowroof castle into a Silver Fortress castle along with a Sleeve Rook formation.

The basic Snowroof formation can transition to a Right King-like structure in which the king and right gold move upward to the fourth file.

Here White can prevent Black's rook pawn exchange by defending the 24 square with their bishop.

However, Yasuhiro Masuda suggests that these are difficult lines and recommends 6...B-33 in spite of the fact that computer shogi engines often play 6...S-42.

After this Black will need to arrange their pieces to construct the Fortress castle and decide upon an attacking strategy.

Since Fortress requires many moves to construct, Black needs to wary that White may attack first.

This is an older opening used in the 20th century up until the end of World War II after which it lost popularity.

White fortifies the second file by dropping the pawn back to its original position at the head of bishop.

Keita Kadokura (White) used a Silver Horns Snowroof castle against Shōji Segawa's Fortress position in a 2017 Ōza tournament on October 22.

The adjacent diagram shows a game position between Hiromu Watanabe (Black) and Hiroshi Kamiya (White) from August 2016.

His bishop has advanced to the 33 square in order to prevent Watanabe from trading off his rook pawn.

His opponent Watanabe is using a Fortress castle (via the tempo-saving Quick Fortress method) that has not been fully completed (his left gold remains on its starting 69 square) and his king has still not fully entered the castle.