Keigo Kurusu

Keigo Kurusu (来須 圭悟, Kurusu Keigo) is the Fourth diary owner, and initially introduced as an ally to Yukiteru Amano and Yuno Gasai. As the Chief Inspector of Sakurami City's police force, Kurusu uses his "Criminal Investigation Diary" to predict the crimes that he will investigate, using its power to identify other diary owners.