Some countries actually has ISPs that offer unlimited bandwidth, japan should have some as well. Even here on a third world country, theres one that offers a really cheap one for a good price ( around 22$ For ~30mbps for the cheapest one. Can be upgraded to 100mbps, but I dont know the price. For 5-6 streaming, that should be enough. ) And since this is fiction, its probably cheap as fuck or sth.
If YouTube has taught me anything, having a bunch of internet celebs living in one house trying to keep secrets from each other isn't going to end badly at all...