Kubo has made an official announcement on twitter:
【お知らせ】明日木曜夜、今から約24時間後にTwitterアカウントを一旦削除します。ご用の方はそれまでにDMでお願いします。
Basically he’s saying that tomorrow (24 hours from when he posted this, 17 hours ago as I write this) he’ll be removing his Twitter account. In an earlier tweet he posted that he doesn’t really know what to use Twitter for any more so he’s just going to get rid of it. Lulz.