japan was / is by far easiest faction to play from br 1 to 5.
Sure, i did that “grind” months ago but didnt really notice too many frequent incidents of getting stomped by murrican stacks. Arguably biggest “balance” issue was the murrican planes spawning on sky and JP planes having to take off from carrier.
I just stick to BR2, there aint much anything in between BR2 - BR5. Grind the BR5 equipment ready and then move on to BR5.
Sure this highlights the lack of equipment in JP tree.
But that was actually the thing I liked most about JP tree, no tons of duplicate mandatory grind shit.
On BR5 JP could hold its own just fine against murrica.