けておめでとうございまったそうだ
akete omedetōgozai mattasōda

Interjection
Evidential Auxiliary

Expresses hearsay about a past event ("I heard that...") of 明けておめでとうございます

1. It is said, "Congratulations on reaching adulthood."; I heard congratulations were given for reaching adulthood.

Past/Perfective
Hearsay Evidence