Niwa was born in 1974, and after graduating from the Faculty of Law at the University of Tokyo he worked as a director at Japan Broadcasting Corporation (NHK). He completed coursework for a doctoral program at the Graduate School of Human Sciences of Osaka University, but left without a degree. He then began serving as associate professor at Hosei University Faculty of Social Sciences, and has been in his current position since 2008. His research interests focus on media, journalism, and popular culture.