Koume putting a cursed kiss on the letter was adorable, Marie really means the world to her.
Also divination must be really amazing. Instead of going the roundabout way, Marie could have sent just a letter with a gift, but I guess it wouldn't have been very flashy and it wouldn't have made such an impact. Peering into the future, observing the present - through her magic she is telling Koume that she is always watching over her in a very literal sense. Incredible. Knowing that something like that exists and that someone you really care about is there for you through it must feel incredible.
Thanks a lot for the translation. I just binged the anime and absolutely had to read the manga and I'm very glad there are translations.