Once an obscure niche market, Japanese comic books, known as “manga,” and animated series, or “anime,” are becoming increasingly mainstream. Comic book fans laud the adult themes and storylines, often branching out with “fan comics” of their own — installments in a series written by American fans, most of whom don’t speak or read Japanese. At annual conventions like AnimeNEXT, which took place in June in Secaucus, and MangaNEXT, which runs this weekend at the Doubletree Hotel in Somerset, thousands of artists, dealers and fans of manga and anime gather to wield swords, shields, demon claws and other varied magical objects in tribute to their favorite series. (Video by Nyier Abdou/The Star-Ledger)