Now comes the hardest part of your journey and that's actually writing the damn thing.
The most important chapter of every novel is always the first one. Reading novels is a huge investment of time and most readers use the first chapter of a novel to determine if they are going to continue to read your novel. So, what are we going to put in our first chapter? EXPOSITION!
We don't need to start with an exciting event that kickstarts the plot and instead will start it with a huge exposition dump. After all, the readers will have to learn that stuff anyway so better put it at the beginning of the story.
What is that exposition about you ask? It's about the most important thing in the story of course. THE PROTAGONIST!
Every good story should start with "Hi my name is [insert extremely generic name here]." Nothing is more important than explaining the MC's extremely boring background, appearance, and that he is a weeb so we can have an excuse why he is going to our favorite anime worlds and so he can know the plot of the story like you. This part of the story is very important, I mean just imagine how lost the reader would be if he didn't know those extremely vital details! Also, don't forget the purple prose!
Yes, we do break the rule of "Show, don't tell" (That if we want the reader to understand or belives something we have it to them and not just tell them. For example, instead of saying that a character is evil, it's much better to let him commit an evil act in the story. The same goes for worldbuilding. It's better to show the readers how the world works instead of telling them how it works.) , but we are too lazy to come up with an interesting way to introduce our MC to the readers.
However, if you do want to introduce the MC while kickstarting the plot, remember to use the most cliche and cheesy plot you cant think about. Make it so the MC saves an attractive woman who is an omnipotent goddess or the daughter of an omnipotent god and saves her from the most cartoonish bank robbers or thugs (even though that would raise the question of why she didn't defend herself if she is an omnipotent or daughter of an omnipotent being and why and if she really is powerful enough to give the MC insanely OP abilities or is protected by someone who has them why was she scared of norma humans?). Or you make the MC die an absurd death that will make a random god of the multiverse laugh for some reason and decides to reincarnate him as thanks (even though there are many funnier people and things out there and in the whole multiverse the MC was the only one who could make him laugh?). Or you could use the good old Truck-sama and make the MC save some random people and get rewarded by some god for it with a new life (even though there are millions of people out there in the past and present who are MUCH more deserving of it than the MC).
Anyway, no matter how you do it your MC will always die in the end and meet R.O.B. (short for "Retard who is Obviously Braindead"). Whit that, the plot of the story is kickstarted and the MC journey can finally begin.