Althrough Japanese heavy tanks greatly differs from Japanese medium and light tanks, they all share few similarities; All Japanese tanks have great gun depression, (with exception being Chi-Nu Kai and some heavy tanks that have limited depression above their miniturrets), lack of sloping on armor (except on tier 8 - 10 medium tanks), and good firepower.
Japanese medium and light tanks have few more things in common. They all have poor armor thicknesses, however, higher tier mediums (most notably the STB-1) have sloped armor, which may result in lucky bounces. They also combine good gun depression with guns that have excellent penetration and a good balance between alpha and ROF. In the first few tiers, the Japanese tanks can seem to prove to be a real turn off. Guns have generally average accuracy and handling. Most Japanese medium and light tanks have decent camo values for their class.
At tier II, the line splits between medium tanks and light tanks. Japanese light tanks offer good speed and agility, culminating into the Type 5 Ke-Ho, which is small, fast, agile, and packs a surprising punch. However, to balance these overall good characteristics, the three light tanks in the Japanese line lack in armor even more so than their medium counterparts, and are not exactly specialized for active scouting in general.