Arakurayama Sengen Park/Oshino Hakkai

Hi everyone
Having figured out my Hakone itinerary, I'm now looking at how best to hit a couple of other areas in the Fuji region. I would be coming from Tokyo for the day and want to spend some time in Arakurayama Sengen Park (to see the pagoda) and perhaps also Oshino Hakkai.

I thought of doing a tour but can't find one that doesn't double up on things I'm already planning to do in Hakone.

What's the best method to hit these spots, and is there anywhere else you recommend I could go to fill the day (not really interested in Fuji-Q or Grinpa).

Thanks again!