Japanese Heavy Tanks were added in Update 9.10. It contains mostly designs that had never been blueprinted.
The Japanese Heavy Tank line starts at Tier 3 (making it the only Nation to have a Tier 3 Heavy Tank), and goes all the way up to Tier 10. Their tank as very unique. In the beginning, at Tier 3 and 4, they have Heavy Tanks that play like a slower Medium tank, with low pen, high rate of fire guns. Starting at Tier 5, the Japanese get very large machines (most are equal to or larger than the Maus (which was said to be the largest Tank in WoT))