[DecoyBlackMage]

Well, Build had a similar human survives thing at the start, but that did not last forever and turned humans eventually started dying, tbf some died at the start as well due to their weak constitution.

So I would not be surprised if the Raid Riser eventually starts killing the users.

In regards to the ZAIA arc, it seems to be just build up, while the front of the episodes are so far Aruto and Gai, the main plot direction is happening in the background with Fuwa and the one giving out the Raid Risers, which is fine, Aruto is not really aware of it yet, Gai seems to be smelling a problem, but is likely far to arrogant to really think it is going to be a major one, which will likely cause massive devestation.

Either way, slow build up.