You can bypass that by overwriting the region cookie that gets assigned to your browser(Google it). They changed that system a few months ago, so you'll probably have a hard time signing up to any new games on DMM with your current browser cookie.
I don't know if DMM is just xenophobic or if it's a measure to help ensure compatibility with the games. A lot of DMM games do use your computer's system clock for displaying event timers - I know it really throws off the Burst Time countdown display in Kamihime if you're not on JST(it's an hour long phase, twice per day, but it will show silly numbers like 899 minutes remaining).
(Burst Time, in Final Fantasy terms, is where you basically get to start every battle with full limit-break meters for an hour. A lot of people tend to trigger/farm bosses during these periods for obvious reasons.)
Love(infatuation) is often one-sided. =V
Character Design aside, I think she's a solid pick. Dark and Light type Kamihime are fairly uncommon and, if we get the pre-reg's associated weapons, you'll get a dark staff that is useful for healer and caster-type heroic spirits/avatar classes. You can get SR weapons of every other element, including light, just by clearing the main story and trading the treasure drops from each world. (Wind is a sword, lightning is a spear, etc.)