Alright, I expect this will be the last poll before I start working on writing this story.
And this is an important one.
Normally, I wouldn't consult with people for this, since it's part of the build, and I always just do my builds as I see fit to make the story work as I envision it. However, in this case, it's kind of important.
There are four options, all relating to a very important detail: how much do we want the MC to game the system?
Option One: Hard Mode. He starts in the New World/Real YGGDRASIL, which means that Nazarick is around and so is Momonga. That means that he's having to contend a lot of very powerful enemies in the long-term, or otherwise has to convince them to let him capture them or some such. No mean feat, given many of the Guardians are the same Tier as Sesshomaru is and Momonga is a tier higher.
Option Two: Veteran Mode. He starts in the New World/Real YGGDRASIL, but he does so using the difficulty option that Nazarick doesn't exist. Now, that might make it seem like easy mode, but what it actually means is that all of the high-value capture targets and powerful items that come with Nazarick are out of reach. That will severely crimp his budget and waifu options, which is why it's still a semi-hard mode.
Option Three: Filthy Casual. He enters the 'real world cyberpunk dystopia' that all the players live in, gets Cortana to hack the shit out of things, and sets up his own account and character with overpowered items and what not before the 'transfer' happens. As a result, he has both the challenge of Nazarick but isn't starting with nothing either.
Option Four: Cheating His Goddamn Ass Off. He enters the world as Momonga's IRL player, giving him control of everything right from the start, and he uses race-swaps and shit to not be a skeleton. Probably the least fun narratively, but fastest access to 'plot' and the ability to change worlds pretty quickly if we're so inclined. Though it might not be without it's challenges, if I decide to throw in curveballs to keep things interesting~!