MC's been alive for more than a 100 million years but still acts like a teen. Judgement after reading the first few chapters: trash. Is trash bad? Up to you. I like trash, but this story hasn't introduced anything interesting in the first few chapters. The 'trained for a 100 million years' thing has almost no impact on the story beyond giving the MC the ability to show off some special technique when he decides it's appropriate.
As far as I can tell this is a poorly executed look-at-me-I'm-special power fantasy with a couple of uninteresting waifus thrown in. Normally I'd love such a story, I'm shameless like that, but this story is all in all boring. There wasn't a single characters in this story that I actually found interesting and wanted to see more of.