It's Sudden, but I came to Another World! But i hope to live Safely

"Understanding" is "Stronger" than a Sword! There is no magic without any weapons!
But! This is the story of a man who wishes to live safely!
"So, I've come to a different world."
That man stood alone in a mountain full of plants and creatures that he never knew nor saw before. He goes down the mountain by avoiding encounters with a big slime (and bandits), and is caught as a suspicious person in the castle he reaches. In interrogation the female knight Ilius met at the imprisoned place, when talking about the bandits seen in the mountain, Irias, who was stuck in the search for said bandits, hurriedly strikes the bandits . My wish to be a brave man, or to build a harem?
"I just want to live in a safe place" - a story that such a man survives the different world with "Understanding" as a weapon!