If you want to hang out with Japanese girls casually, I recommend you to use Escorts in the city.

Unless it is a small town, all cities have a few Escorts at least.
It is surprising that those Escorts have college students and married women.
It surprised me more that they told me they work as part-time job.

I met a college student who had not worked for Escorts once.
You can meet Japanese girls of your type in Escorts much easier that nanpa pick up in a city.
And you probably can request things to part-time escort girls that you can never expect in nanpa.

There is a possibility you can meet infamous TV stars in Tokyo and Osaka.
You cannot meet stars, but you may see idols who are not featured yet.
Who can complain pretty Japanese girls you see in movies or dramas serve you?
You will think how lucky you are.