noun
Mary Sue novel; wish-fulfillment story
Internet slang for a genre of web novels, especially from the site 小説家になろう, where an ordinary protagonist gains overwhelming power or success with little struggle. Often used critically.
最近の異世界転生ものは、なろう系と呼ばれることが多い。
Recent isekai reincarnation stories are often called narou-kei.
あの作品は典型的ななろう系で、主人公が最初から強すぎる。
That work is a typical narou-kei story; the protagonist is too strong from the start.