Apparently, his oshis are Lyrica (Millie) and Coco. Millie is actually the only Niji member he follows, so I guess you could say he's a fan. As for his popularity, his videos gained traction but they didn't translate well to live viewers. Kind of in the same boat as Sunny, now Kunia, in that they had a big subscriber pool but people didn't stick around.
The dude is cringey, but I wouldn't take most of what he says seriously. If he didn't change his entire personality, then his humor is definitely hit or miss, and his flirting can be a bit much, but if you can overlook that he's pretty genuine.