Actually, the most important change was made by Tsunamasa's son, Ikeda Tsugumasa, who built the Yuishinzan Hill (in the photo).
The hill, covered with grass and dotted by decorative rocks, azaleas and rhododendrons, was a big improvement, creating a more dynamic landscape and at the same time offering a broad view of the surrounding garden.
EXIF info:
Nikon D300
Lens: 8-16mm F/4.5-5.6G
Focal Length: 9mm
Aperture: F/7.1
Shutter Speed: 1/1000s
ISO Sensitivity: ISO 200