It depends on AC really if the agent is willing to check you in only to NRT. But you might be able to ask check in agent at YVR to check all the way to PER. My suggestion is not to as there is too many connections and you may end up with 2 luggage tags !

If the layover at NRT is short, you will have problems. If not, then that might be the best solution.

As you have 2 tickets, and even though you are connected through from YVR, MH *may* ask you to pay for the excess based on your ticket allowance being only 20kg. Just be prepared.