***WARNING - MUCHO TEXTO COPIUM AHEAD***
As someone who once upon a time watched primarily Niji I'm still clinging desperately onto the copium train that none of the livers were involved and it was all management.
Nina was the first and still my favorite Niji liver, by the time I started watching her she was already close to the rest of Ethyria. Looking at older vods I could see some awkwardness between her and the rest but I didn't think much of it beyond still not knowing each other while Millie and Enna especially were already close. I've seen rrats about the clique for a while but my assumption was not so much "Mean Girls" type shit as much as these some members were already on good terms before joining Niji and thus naturally gravitated towards each other. I tried not to hold to much trust in 3rd hand knowledge from a bunch of autistic dudes on the internet who have a poor grasp on friendship in general, especially women's friendships. Ethyria at the end of Nina's stint really comes off as a very close knit group and I know she still hangs out with them even after leaving. Nina/Matara's talked about why she left Niji now that she's settled in at Vshojo (burnout was bullshit unsurprisingly) and did state it was due to harassment of her and the Honey's but it sounded more like it was due to Nijisister harassment and not harassment from other livers. I'm gonna hunt for the vod where she brought it up so I'll edit this if I'm wrong.
I know Selen never collab'd too much with the female livers outside of Pomu and Rosemi but to me that always seemed more of an issue with the game's they play being so different as opposed to any sort of internal drama.
The other members I watched consistently are Rosemi and Scarle and they always seemed to stick to their own stuff more than collab with the rest of Niji. While that could be a sign of them just tuning out completely from clique bullshit it feels like stretch.
Tbh the only member of Niji I ever disliked was Kotoka. She always came off as a Snake and someone willing to do whatever she could to get in managements good graces. Especially when it was found out she was a JP who joined EN to get around VTA, don't get me wrong it was smart of both her and Meloco to do but does show underhandedness from the beginning. She only streams in En maybe once a week, she's already a JP in everything but name only and is probably willing to do whatever management asks for the chance to become an actual JP. It's also why she's probbaly not as worried as the rest if EN continues their current trajectory and dies cause they'll be moved to Niji regular and like with KR the ones who speak JP will all be fine. But even on the slim, slim, slim chance she harassed Selen on managements behalf I'd question if the harassment from a single member could drive Selen to such extremes.
As much as EN complains about management it'd be surprising if there's an inner clique that bows to the whims of management. A lot of the members are constantly bitching about management during streams and it's even more prevalent during any sort of zatsu-type collab, the upside of management not caring about them is they can get away with it cause unless someone reports it directly they aren't ever gonna see that shit.
All that said I trust what Selen says and if when she's back as Dokibird she specifically mentions harassment from livers I'm gonna feel like a jackass for defending them. Thanks for coming to my TED Talk.