A few game-related issues.
1. One of the things that surprises people who study World War One, The First World War, or WWI as many people like to call it, is that in that war, the Japanese Empire was actually allied to the British Empire. It took British imperial sensibilities, a few diplomatic blunders, and time for political tides to change for the Japanese government to finally side with germany and sign the pact that created the Axis Powers of World War Two. That happened in the mid to late thirties in our world, but in the world of our game, I propose that developments along those same lines occurred a bit earlier, to wit, some time before the beginning of the game, most likely two or three years before, most likely as a result of a major diplomatic fiasco between Britain and Japan. What that was may or may not come out in the course of the game; I'd prefer to avoid it simply for brevity's sake, unless it becomes integral to the plot, but what happens, happens. The relation to the game is that Merovingia, whatever else she may have become, was originally the fine;ly-cultured daughter of a diplomat in a British colonial settlement in China; thus, though her parentage is mixed Erasion, and she looks like a finely beautiful Chinese woman, she nonetheless, at the time she was thrust through the dimensions, spoke with a British accent, and was thus accepted as an ally and an expat resident of sorts of the island community in which she found herself.; there was therefor e a slight "in" for her to be adopted by the Elder.
2. As implied above, Meri is a time traveller, albeit an inadvertent one; it was not her choice to fall into the wormhole caused by a titanic electrical storm over the Caucasus that struck at the same time that she and her airship of vampiric "commandos" attacked the St. Elmo, with orders to kill Commodore Dreyfuss and his crew, and destroy his ship in order to prevent a future event from occurring. Not her choice, but it's what happened. She fell through into the universe of the Duckpond, fortuitously in the locale of the village of Shouma Youkai
3. Yes, I'm aware that my use and knowledge of japanese language, lore and placenames is execrable at best. To the best of my knowledge, none of the names I've used so far are actual names, or names used by any other author, save such forms as Youkai (admittedly borrowed from anime) and Shi onna and Koromi. I'm aware that Koromi Shi-onna means something other than "white bat"; According to what I've looked up, "Koromi' is "bat," and "Shi-onna" actually means something close to "fourth-daughter," thus fourth-daughter-bat; thus the elder is naming her formally as one of his daughters, that is, an adopted daughter... er, if I've got the language right, which is by no means certain. He is not using the Japanese term for "white bat" because I admittedly did not think I was equal to the task of stringing that all together (such term might not even exist in the abstract sense).
4. Apologies to anyone who reads this and sees my poor attempts at Japanese language and lore.
5. It's worth mentioning, in my opinion, that Japanese lore does not actually allow for the existence of vampires; similar beings, yes, but not actual vampires. that's actually a borrowed western concept that has taken root in japanese popular culture because of public fascination with it in the entertainment industry. Just saying.
6. Finally: I'm not a weeaboo. I just like vampires and ninjas, find japanese (and all nations') military history fascinating, and Merovingia's a fascinating character. Morganthe (her "sire") not so much so, save as a "progenitor" type.