Obviously not the final name, I just thought it was clever as a throwback to when emails were just getting started. I'll probably keep it this way, but whenever someone decides to write this idea, you can change it. This might not end up as a very usable idea as it's kind of hard to think of a way to break away from the early plot of Re:Monster. I hope you'll be able to figure it out, but it seems unlikely. Its development would also be hampered due to the novel's incomplete state, but the story will eventually finish and then that will no longer be an issue.
Now, I've only seen a single fan-fiction on here about this topic, so there should be some free real estate for more. What I'm proposing here is a reader of the story being thrusted into Goburou/Kanata's body when he first awakens. I know it'd probably be easier to make an entirely new character, but I think the Absorption ability is pretty useful. Yeah, again, you could give it to another character, but why do that if there's someone who already has it. But as I write this another idea pops into my head.
Now, if you've read The Strongest Saiyan God then you'd be aware of Genetic Access and how OP it can be. If you don't want to use my previous idea, and want to write your own character, then use this. The problem comes in when you take Evolution into account, but we can alter some of the characteristics of said mechanic to better fit the ability. We could remove levels from the MC and make his evolutions completely dependent on Genetic Access, bypassing the need to reset his gene limiters every time he hits max level. It would also make him able to evolve into whatever species he wanted, instead of having to rely on environmental/physical requirements. And I think this would also remove any chance of receiving a blessing from a God/Goddess, but he wouldn't need it as he'd already be plenty strong on his own.