Anri accidently destroyed the multiverse after Arkial was killed. They both escaped into the Mists, as did their friend Basta, albeit separately.

They were all reincarnated in the next/ current(?) multiverse with their conciousnesses intact. Anri reincarnated as Holly, Arkial as Matt, and Basta as a kid named Iris. Anri and Arkial were silent during Holly and Matt's life until they were Misted, while Basta manifested as Iris's "imaginary" friend who never went away.

Basta is normally humanoid