Took it to my local shop today and they said it was the rear main seal. Estimated repair cost of $1,400. fml
Shop said to keep an eye on it to see how much is even leaking, so going to put off this one for a tad longer. Just spent $2k on 4runner last month for a brand new Power Steering Rack Replacement.
Plus 4Runner is only going to be driven about 2k-3k miles this year (work from home, plus two other cars).