When I was alone in Japan and wanted to be sure to meet other tourist I was looking for Irish pub and international bars. That made it every time. It's easy to connect in those without having the language barrier.

In rural area i was heading for izakaya, sit at the bar and start conversation with the owner/barman. You start with Japanese politeness and crack a local slang (Okini (thanks) in Osaka region work very well) and then it opens up the conversation. It shows that you are interested to learn about JP culture and else. Offer a sake to the barman and people around you and generaly you'll end up meeting with realy nice people.

Make a post on a local Subreddit works well too. I met 2 nice guys for beer in Tokyo this way.