@Curccoll his another character that he kept as a joke, which turned out to be useful when he didn't want to identify himself. Also, apparently it have its own consciousness and can't be controlled.
@harvest_sinner The official English release of the LN translation have up to vol 3 right now, which is in the middle of the arc the latest manga release is starting. But the LN has a lot on the background of the MC and the Infinity Game that the anime and manga skipped altogether. I'd check it out because it's surprisingly good.
I like the different character thing this story goes for. It's refreshing, not to say it's some amazing new concept, but in this genre it's nice to see something interesting come along.