If you're reading this and are in Tokyo already you should come out to the Hacker News Tokyo reader meetup. It's a great place to find cofounders, talk shop and discuss these kinds of issues. We hold them once a month.
You can sign up here and you'll get notified about the next one when it gets scheduled:
https://hntokyo.doorkeeper.jp/
edit If you're not in Tokyo I know there's one in kansai too: http://hnkansai.org