"There is always the currency risk but the interest is incredibly low."
Yep that is how they lure you into these sort of deals..
Such arrangements usually requre you to maintain a certain LTV level such as 75%
So for this case if Euro was to drop by 10%, the bank that gave you this Yen loan will demand you manintain the 75%LTV, usually they give you 2 weeks to settle the LTV breach...