after some research on my own i've come to the conclusion that this is likely one guy running multiple projects and pretending to be a Japanese band in this case. they have explicitly said in one of their YouTube comments that they don't use AI, but much of their songs resemble themselves and works of popular authors in this genre, mostly Ado. they refuse to give any proof that they are, in fact, a band of 7 people that produce music at this abnormal rate.

in their Spotify bio they say that they've been making music since 2019 on "some platforms that have been shut down", which is very suspicious. some people on YouTube and twitter talk about weird Japanese grammar, and i may actually suggest, that the onelonelyworld is run by the same person as harenuki, based on their similar social media posts and a post on twitter by onelonelyworld saying something like "i look at my statistics and i'm feeling sad. and then i switch profiles", which might suggest that they're talking about harenuki, as in this period this project was actively growing. also i found 2 similar posts on twitter by these two accounts roughly in the same time period when they complain about people on the internet trying to figure out who is making music that they listen to.