For this achievement, you only need to destroy
5 enemy tanks with only
5 Japanese tanks each, no matter if it’s a
Tank Destroyer or
Light Tank, to know how many tanks you’ve already destroyed with each tank you can go to
Stats in the
Multiplayer menu by pressing
and then select the
Japan, it’s faster to do with
Tier I, the 3 tanks in
Tier II and one tank in
Tier III.