isekai-kei
The rash of light novels/anime with similar recurring themes involving the main character, typically a loser or normie in IRL, suddenly transported to another world by some means in which the character becomes a hero/heroine of the story.
The influx of
isekai-kei storylines comes from wannabe light novelists who uploads web-novels and stories involving this situation because it is the most easiest to write, with publishers themselves taking up and publishing these stories because it's a formula that works for now and anime companies taking up these titles in hopes of churning easy profit.
Not-so-good-example
People be talkin' that
Zero no Tsukaima was the OG isekai-kei don't know that
Aura Battler Dunbine was the real OG isekai-kei anime and it wasn't moe, it was hardcore mech!
Aura Battler Dunbine OP:
http://www.dailymotion.com/video/xhcyn6