Sadly, not all isekai fantasy stories these days are as harmless as So I'm a Spider, So What?. The concept has always been a playground for male power fantasies, and these days it seems the fantasies are taking more and more from both hentai doujin and the darkest parts of their creator's minds.
THE RISING OF THE SHIELD HERO (Tate no Yusha no Nariagari), based on the light novel by Aneko Yusagi & character designs by Minami Seira, with art by Aiya Kyu. First published in 2014, and first published in North America in 2015.
PLOT:
Naofumi Iwatani was just another hapless college-aged otaku, but a chance encounter with a strange old book sending him hurdling into a strange, medieval world alongside 3 other young men. They are declared heroes of prophecy and gifted with magic weapons. Naofumi is initially disappointed to get only a shield, but when the pretty young Myne offers to join his party, he believes his fortunes are finally looking up.
Then Myne betrays him, steals his goods, and accuses him of rape. Naofumi quickly becomes a pariah in the kingdom. The only party member he can get is Raphtalia, a half-tanuki girl that he buys as a slave. Together the two venture out into the world to level up and discover what fate the world has in store for them.