It's either the Handle was removed after they quit, or Raika may have undergone an extensive name change and therefore can't be found because no one knows what to look for.Assuming this is the case, I wonder if the Warabi Raika handle was freed immediately/shortly after they quit, or only when the shell parking that handle needed to be re-used. Doesn't really matter though. (Why was Warabi not a wallaby? I am now sad.)
The reason I think it's the former is because SuzumiyaSonata is also available, and he was the first person to quietly graduate from Gen 1 back in February.
The fact that everyone else can still be found indicates one of two things:
A) Roco and Meruto were also freed up, and trolls took them on the same day but didn't bother to take Raika too. This makes sense if not for the fact that Rou is also searchable and he is still active.
B) Warabi Raika has genuinely quit, which means VTAs protocol for graduated members is consistent.
The circumstances are anyone's guess. Raika could have pulled out at the last possible second which left the other channels searchable (because they were gearing up to go public).
Voltaction were active at the same time as Gen 2 for about 2 weeks before debuting. Their channels were made on Jul. 2 while they debuted on Jul. 16, so it's hard to shirk the feeling that a debut should have occurred in the last couple weeks. The question is what the fuck happened.