In November of 2017 me, my gf and my brother took a trip to Isehara City to go hiking. The mountain is called Oyama. For the record these pictures were taken on Nov. 25, so if you are looking for a similar scenery, I'd suggest sometime around that time frame. The mountain was absolutely beautiful. The fall colors were perfect, as was the temperature. Definitely don't dress too heavy or you will get very warm hiking up.
Sadly, shortly after that my brother had to go back to America since his 90 days were up. I took him to one of my favorite izakayas where we indulged in seafood and sake. We had a great time and I look forward to doing it again! Hint hint Jordan!