During the ruckus as the Kaginoji house, Nasa and Tsukasa pledge their love to each other at a church. After Nasa reports to Kaname that he has finally proposed, she points that he still doesn't have a ring. Although he doesn't take much notice at first, Nasa gradually becomes more self-consciousness about the role of a ring in newlywed life.
That means we need three rings total, between 
the engagement ring and wedding rings...
...هذا يعني أننا سنحتاج لثلاثة خواتم، واحد للخطوبة واثنين للزفاف
O sea, que se necesitan tres.
Uno de compromiso y dos de matrimonio.
O sea, que se necesitan tres.
Uno de compromiso y dos de matrimonio.
Donc entre la bague de fiançailles
et les alliances,
Questo vuol dire che servono tre anelli, 
fra l'anello di fidanzamento e le fedi...
Então precisamos de três anéis:
Получается, нам нужно одно помолвочное
кольцо и два обручальных, в сумме три...