Hi @inamori
see that topic, yesterday:
There is no "blacklisted" from Letsencrypt. That user has created a certificate 2020-04-13.
Ask Heroku what that means. Or check, if there is a better log.
Checking your domain - https://check-your-website.server-daten.de/?q=jp.chimeido.net - you don't have a new certificate.