That's really cool--my Monday group is fully homebrew, and it's loads of fun. But even back in the day when we were doing pregen we had a tendency to go a bit off the rails. (We ended up as landlords in Phandelver, and I managed to persuade a cannon-fodder goblin into joining our party, and that's the start... And it let the DM do some "cool stuff" in addition to running the show.

And yes, I deeply, deeply love the manga. It's better than many books I've read and I've managed to convince several non-prose skeptics to try reading it. Unsurprisingly, they all loved it.