I read the prologue and the first chapter. Apologies my feedback for this one might be kinda vague and bad.
- As you mentioned, you're knowingly performing the tropes of an Isekai anime. Which is fine! You might do this in later chapters, but what's the "twist", what's the deconstruction that makes readers want to continue? You might get this to this in later chapters, but getting to it earlier might allow you to hook more readers. ?

- As for the writing, it's a bit overly descriptive in some places for my taste. An example of what I mean, I would get rid of the text in bold (also found a small error that I bolded):
It's great to have so many vivid description, which you do, but I feel that for readability sakes some of them must be cutdown or made more concise. Have you heard of the phrase "Kill your darlings?"
That's what I think would improve your writing the most. It's hard as hell to do, but it's the #1 piece of advice in my opinion.
Overall, I think its a good start. Just that piece of advice, and something to hook readers early on to show that you're performing the tropes, but also inverting them (or twisting them) somehow.
I read the first chapter of Ise-se-Kai 20. I like the concept, it's pretty funny.
And I actually liked the first chapter too, reads like an ecchi manga or something. I don't really have any notes without digging into it way more than I want to do here. There was one passage that could be improved a bit, just for readability maybe split it up or something:
Besides that, no huge notes to be honest. The first chapter sets a solid tone.
I'm a fellow Failure Frame enjoyer. It does make me wonder, how will you differentiate it from your inspiration?