In this line white plays to get a pawn in hand, which is useful if he wants to play positively. But it takes time and weakens his king, so I don't recommend it for white. The main line is quite beautiful:
17... P7e 18 Px7e Gx7e 19 P*7f (The gold is driven back so that white won’t be able to block out the bishop by ... P6f) G7d 20 P9f P9d 21 S4f G6d (White now has a pawn in hand, but it cost two moves and gives black a later possibility of dropping a silver on 7e to exchange silver for gold) 22 P5f P8d 23 S3e (23 P5e is an alternative)
P8e (23... P2d 24 P1f with P4d next so that when the bishop lands on 2f it can retreat to 1g if attacked by ... P2e; if 24 Sx2d? P*2h will win a lance) 24 P4d (or 24 R4f P5e 25 P4d as in Variation II) Px4d (24... P5e 25 R4f as in Variation II) 25 Sx4d Sx4d (25... S6b 26 R4f or 25... S4b 26 P*4c) 26 Bx4d S*5c 27 B2f P*4c
After 27... P*4c
(Black’s threat was 28 N4e S6b 29 S*5c, and 27... P*4d would be met by 28 P*4e G4c 29 S*3b) 28 S*7e! (Showing the downside of the early ... P7e) G4b 29 Sx6d Kx6d 30 P7e! Kx7e (30... K6c 31 P5e! to swing the rook to 7f) 31 P5e! (To activate the rook on the rank) P4d (To block the bishop)
After 31... P4d
32 N4e!! Px4e 33 R7f!!! Kx7f (else 34 G*7d) 34 Bx5c+!! Gx5c 35 S*8d! R*3i 36 S5i
and white cannot prevent mate by G*7e or G7g. One of the most spectacular variations in shogi; black sacrificed two pawns, a knight, a rook, and a bishop for a quiet final mate.