I went to this event a year or two ago, I happened to be passing through japan. It's a very friendly event, real mix of different tech / startup presentations. Would highly recommend it if you're in the area :)
I've not been to the Tokyo meetups, but I certainly enjoyed the HN Kansai meetup. I met some interesting people hacking on (somewhat niche) fun things - game dev, web design, cryptocurrency, etc. Definitely recommend it!
I have one Japan group.[2] Is it you guys? Otherwise, I'd like to add your permanent page to the list.
[1] https://github.com/antontarasenko/hacker-news-groups [2] https://www.facebook.com/Tokyo-Hacker-News-Community-1696102...