Traditionally, when the Static Rook side went for a slow game strategy, they would use Center Vanguard Pawn or King's Head Vanguard Pawn to go from a Boat castle to a Fortress and so on, hence choosing advanced castles, particularly due to the fragility to mate races from the side.
This trend became obvious when comparing the winning percentages of top players – Yoshiharu Habu, Toshiyuki Moriuchi, Yasumitsu Satō and Akira Watanabe – when playing Static Rook Anaguma.
In the Fujii system: It underlies Kenji Kobayashi Super Fourth File Rook strategy as well as Masataka Sugimoto's research.
Although this occurred previous to the development of the Fujii system, the attack on the left Mino king's head is a common goal.
Akira Shima in the NHK Cup playing White against Fujii system won after being forced to build a High Mino following black's B-57, by then attacking the knight's head.
What has turned currently into the prevailing variation in the Fujii system is a so-called new version that came to be as a result of the investigation against Static Rook Anaguma strategies.
If White's lance moves to 12 and the king manages to enter the hole in Anaguma, Black will then attack with N-25, and then P-45 and by opening the bishop's diagonal.
It is characterized by the fact that even though weaker in solidness compared to Anaguma, (white's) king being castled in 21 means not receiving direct attacks on the bishop's diagonal.
For that reason, the Millenium castle that avoided the bishop's diagonal aimed at by the Fujii system's gained considerable influence.
The left silver that formed a Mino castle earlier has been moved to the 47 square to protect the head of the knight that has been developed to 37 for attacking.