"'what door should I pick' was my naive thoughts, but the one who picks a door is me myself"
what? Why does that make it naive thoughts and how is that second half a "but"?
Also, feels like they really could have explained things better to him with those messages. Or that he should have ignored them for a little while to flip through the books and see at least the ToC first (maybe it contained an explanation for the situation?). Either way, he was absolutely right to be cautious when faced with such an unknown situation.
And he never should have done the dungeon quest before reading the manuals on combat. Not to mention finding that growth-type pokemon/golem who would never betray him.
I'm guessing she is the loyal servant?
No, it explicitly said it's not something/someone attractive.