Some actual advice for the OP if he's really with MaHOROBA
You're entering a crowded market. Less so than the japanese market, but the time to really make a move was 9 months ago. You're not the first japanese agency to try to approach the english market, you're not even the fifth.
For example, if you don't have a ton of influence like hololive or a lot of money for ads like nijisanji, your best case scenario is achieving something like say Prism Project has.
https://www.youtube.com/c/PRISMProject/channelsThey're a japanese-owned agency that's targeting mainly english speakers, and the one that's doing basically the best at the moment. But that's mainly due to some good artist choices, luck, and some genuinely clever marketing.
A more average example of opening an EN agency these days would be Phase Connect, which is much smaller.
https://www.youtube.com/channel/UClpOEZoIYhxIY6n5NNGaPbA/channelsNow when it comes to talent recruitment... People that watch vtubers in the west are weeaboos. They watch anime, read manga, and jack off to japanese porn. So if you can get an actual japanese girl that speaks english, then that's basically the dream girl of every weeb and it translates into viewership. See the above phase-connect example. The girl that's twice as big as everyone else? Japanese girl that speaks english. I know bilingual japanese girls are a rare commodity though, especially for a small agency like yours, so if you're recruiting western girls you should probably be careful to keep a "no politics" policy. The last few years have seen politics become increasingly more partisan so hiring a girl that expresses strong political opinions one way or the other is liable to see half your customers drop the company.
Finally, you're going to have to find a way to get exposure in the western market and that's the hard part. Generally it's a good idea to get artists that worked for hololive. In particular it seems people will watch any vtuber that Nabi does art for. Beyond them, the only artists that are somewhat known in the west are likely to be far beyond your budget like yaegashi nan. Running ads is slightly less effective in the west due to adblockers, and there aren't any dedicated news sites that cover vtubers like in japan. Over here it's mainly anime sites that report on vtubers, and they mostly report on the established ones(so they might throw your initial PR about debuts in the trash).
You can basically shill for free here and on reddit and to a smaller degree on facebook, but exposure isn't really easy unless a big clip channel happens to pick up one of your girls. And that basically comes down to luck
