@nyaasar Though it might be considered as an Alternate story both here on Mangadex and Magaupdates. It genuinely feels more like a prequel, rather than an alternate story, because in the original it's shown that he knows how to organize a party and that he was already acquainted with Iris, to know how she looks and fights in human form
While in this story, this is the first time the MC and Iris met, and he also doesn't appear to have a lot of leadership skills, so much so that he's so far by now doing everything himself and asking everyone else to see how he does stuff
So basically, this story by the amount of information we have so far, it's most likely to be a prequel, about him trying to push whatever limits he can of his crest with companions (since he already said he already hit the cap of his crest physically). While the main story is about after he tried to do everything, even partying with others (aka this story), so he takes a gamble of getting his desired crest by reincarnating, which succeeds
This is also proven by the fact that in this story, he looks far younger than when he's shown in the first chapter of the main story, proving that it's likelihood of being a prequel higher
