JR Pass is worth it. If you travel from Tokyo to Osaka round trip that will nearly cover the price of the 2 week pass. My family just came here and they all had passes where as I was paying out of pocket for every ticket. The pass covers reserved seats too which are quite a bit more expensive. If you're flying into Narita you can use ride the Narita Express into Tokyo or Shinjuku station with the JR Pass which is like 3,000 yen one way. Which by the way if you're coming into Narita I really recommend spending a day checking out Narita-san temple. It is true though that there is less JR lines in Osaka but you can take the JR line to Nara from Osaka which is really awesome if you haven't been. The price will most likely be covered completely in what you plan on doing and its also nice to have that option of hey maybe i want to make a day trip to hiroshima or something.
As far as the dating thing, I have to agree tinder will be a good bet in Tokyo even though I dont use it. You probably wont be taken very seriously if you're just here on vacation from normal girls. So don't expect anything serious besides going out to eat and drink or a hook up. If you dont have anyone to hang out with dont hesistate to go to smaller bars in tokyo by yourself... you will definitely meet people and make friends that way. There's always the club option too if you're trying to meet some girls but I don't know if I'd go to a club alone! Anyways just have fun and enjoy your time here. Not sure how good your spoken Japanese is but don't let it get you down if stuff goes over your head... just smile and keep having fun.
As far as the dating thing, I have to agree tinder will be a good bet in Tokyo even though I dont use it. You probably wont be taken very seriously if you're just here on vacation from normal girls. So don't expect anything serious besides going out to eat and drink or a hook up. If you dont have anyone to hang out with dont hesistate to go to smaller bars in tokyo by yourself... you will definitely meet people and make friends that way. There's always the club option too if you're trying to meet some girls but I don't know if I'd go to a club alone! Anyways just have fun and enjoy your time here. Not sure how good your spoken Japanese is but don't let it get you down if stuff goes over your head... just smile and keep having fun.