So how did Bloodmoon Ursaluna manage to survive into the present day?

We are never outright told how he has managed to survive into the modern day (with him being from Sinnoh back when it was called Hisui making likely hundreds of years old and he somehow got to Kitakami by sea) other then it being possibly hinted that it has something to do with his Bloodmoon form and even then we don’t what caused it exactly other then it having to do with Kitakami’s environment. So I wonder what are your theories as how he managed to survive into the present day?