Juugo's classmate. Tensai is smart and into solving puzzles; she aspires to be a master detective and refers to herself as such. Though smart, she is difficult to communicate as her thoughts go too fast for her to fully express them. She moves into the apartment next to Juugo's and becomes his neighbor. She knows that Jūgo is connected to Matsuri and declares him her rival, and thus frequently follows him and even occasionally wishes that events lead him to criminal activity. Her Nanana Collection is a charm which is rumored to have exorcising ability.