We perform regular maintenance that involves service outages every 3 months.
Please check the following page for details.
▼ [Updated regularly] Overview and schedule of regular maintenance
https://help.teachme.jp/hc/en-us/articles/51961436086809
Related:
How are notifications made when new features are provided, features are updated, or maintenance is performed?
https://help.teachme.jp/hc/en-us/articles/6478511346073
Can I change the email destination for contract renewals, maintenance, etc.?
https://help.teachme.jp/hc/en-us/articles/900005508066