Should I buy JR Rail Pass? VERY VERY CONFUSED!

Very Very confused.
First, please have a look at my itinerary.
I will land on 25th September 12:00 PM on NRT airport.

25-26th Sep - nrt airport to shinjuku. 1 Night Tokyo Night Stay
26-27th Sep - tokyo to Kyoto. Goin District stroll/bamboo tree etc. 1 Night Kyoto.
27- 29th Sep - Dontoburi-Umeda-Universal Studios-etc - 2 Nights in Osaka.
29-2nd October - Tokyo- local exploration(Teamlabs/akhiyabari/shibuya etc) - 3 Nights

And on 2nd october - I have flight back to my country from NRT airport.

1. JR PASS ALLOW YOU TO TRAVEL CONVENIENTLY INSIDE TOKYO/OSKA and Kyoto??

Should I buy JR PASS OR NOT??