Tensai Ikkyuu

She is a high-school student who is a self-proclaimed "Master Detective," for obvious reason that she has very good observation and deduction skills. However, she would also find herself in trouble with the island's police, not because she is a young offender, but because of her habit of intruding in to their investigation whenever a crime happens on the island. She has an assistant named Daruku, with whom she maintains sort of a Sherlock Holmes and John Watson kind of relationship. Later on, she and Daruku transfer to Juugo's school after a brief visitation and a little bit of interrogation where she retrieves a stolen item which is part of the "Nanana's Collection" that the latter mistakenly took. She also becomes a member of the school's "Adventure Club."

(Source: Otaku-streamers)