Japanese horses (actually ponies) mostly came from central Asian pony stocks brought to Japan in the third century AD by Koreans, and again in the 13th century AD by the Mongols. Arabian stock wasn't introduced until the 16th century.
These were generally small animals averaging about 13 hands (52 inches/132 cm) high. Compare this to horse breeds typically used by European cavalry which genrerally stood 15-16+ hands high(60-64 in + / 152-163 cm +). Also, ponies have different body proportions than horses typically used for cavalry. A light horse is taller in the shoulder than the body length, and may have a back longer than the head. A pony and a heavy draft horse will have a body longer than the shoulder height, and a back shorter than the head length.
With this in mind, the figure's horse is probably accurate.