I'm just guessing but instead of the OP ring that the HQ has given, this is just a normal ring. To show that they are not provisional married but actually married.
I'm waiting for a R21 book.
Since it's more or less regulated that I have to have it on normally too...Ah- Ooicchi~My~! Good morning~G'morning... wait.You've got your ring on.You haven't been wearing it for so long.Ah, you mean this?Hee~And besides...My oh my~?Eh-