This is 5th version of Zenigata series. Rai Zenigata (Saori Koide) is a cousin of other 4 Zenigata sisters: Ai, Rui, Mai and Rei. She looks an ordinary high school student. In fact, she is an ultra-smart detective with IQ180 whose grandfather is the Superintendent General of the Metropolitan Police. She and her partner challenge to solve many difficult cases by using mobile phone.