The conference has been delayed to a new date September 3-5, 2020, read the announcement.
We decided to postpone RubyKaigi 2020 due to the COVID-19 outbreak. See the announcement for details. #rubykaigi— RubyKaigi (@rubykaigi) February 29, 2020
新型コロナウィルス感染症に伴う状況を踏まえ、 RubyKaigi 2020 の延期を決定しました。詳細はアナウンスをご確認ください。https://t.co/uN3X48tKTW
Many events are delayed and cancelled in Japan from this sheet.
アナウンス無し No announcement 検討中 Discussing 実施予定 Planned as usual 延期 Delayed 中止 Cancelled オンライン開催 Online
Nippon Travel Agency is the official travel agency for RubyKaigi 2020.
Check availabilities from Nippon Travel Agency at here.
Recommend to book with Nippon Travel Agency.
I also did some research for you:
Feel free to contact me for any question.
Hope this helps!