Sentence:  Looking at anime charts, there's always the harem series with the dense hero and a bunch of girls whose personalities are pulled out of a set cast of tropes (the Childhood Friend, "Tsundere", <WSD>"Yandere</WSD>", and Lolita, for instance). 
Meaning of the word marked with <WSD> tags:  A character, usually a girl, who fits the archetype of being genuinely kind, loving, or gentle, but suddenly switching to being aggressive or deranged, often homicidally so.