I talked about Belmond as the 5th most popular Nijisanji male VTuber and I figure I ought to highlight the other 4 in terms of how they've grown in popularity by associating with others.
Hayato Kagami only recently beat out Belmond in subscribers with his recent 3D debut stream, but he's always been decently popular.
He's part of the the music unit "le jouet" along with
Ryushen (arguably the most popular music-focused Nijisanji member) and
Kakeru Yumeoi, regularly releasing covers and original songs.
Kagami is actually the main instigator of most of the Nijisanji ARK conflicts, which is why it was literally like a Game of Thrones event with alliances, war, and negotiations. Folks would tune into his channel because he'd likely be the one to start something. When the four strongest forces in the Nijisanji ARK server were having a conference, Kagami decided to take that chance to abduct a key VIP that the 4 empowers swore to protect. His tribe held the VIP hostage in exchange for materials that would speed up their tech tree for more advanced weaponry.
(This channel translated a decent amount of Nijisanji ARK clips,
here's their playlist)
He collabs regularly with other male VTubers like Kuzuha for Duel Masters, as well as the two VTubers he debuted alongside,
Yorumi and
Fuyuki.
There was a "Nijisanji Men's Project" competition that garnered 400K views, which had male Nijisanji members voice act scenarios against one another, and a panel of female VTubers would judge who was better. Kagami entered with a Doctor scenario.