The tramp stamp tattoo unfortunately doesn't look very hot. It looks like a bunch of weird squiggly lines so we at least know that this art asset wasn't intended for the purpose of it being sexually appealing despite it's location. If it was on the front you could argue that maybe it's intended to suggest something else, but even then it's not a design that's particularly made for that sort of appeal.
The aesthetics of tattoo aside. Congrats you get the speed up your training regiment and you're no longer keeping it absolutely secret. That's cool. But dude, you already know that the other kids in school look at your book as just an empty book, so you're just looking like some try-hard Chuunin right now, and that's within a world that has sword and sorcery.
Also how the hell did they not notice that giant boss slime until now? Everything is indicating that they're inside a wide open room, not navigating around a corner.