That is correct.
The phrase has an origin similar to one I touched upon in another book club thread:
This expression also relates to this older Japanese government, where ministers were on either side of the emperor. The Minister of the Left (standing to the emperor’s left side, from the emperor’s perspective) held a superior position to the Minister of the Right (standing to the emperor’s other side).
The expression here appears to be saying there is no one to the right —「 右に出る者[が]いない」) — so I wonder if that means Fukumaru is so superior, that there isn’t even someone in the subordinate position.
I don’t know if my reasoning is correct, and whether my left’s/right’s are accurate. You can read a little more here:
It doesn’t go very deep into background, though.