Riko Mine Lupin the 4th (峰 理子 Mine Riko) is a female student of Butei High school. She is a friend of Kinji's, whom she calls Ki-kun, and is enrolled with him in the Butei Inquesta department. She is ranked A (Second highest rank). Although known as the biggest idiot in Kinji's class, she seems to hold a lot of information including info on the students of Butei High school. She likes customizing her uniform into Lolita style and playing dating sim video games. Her weapons of choice are double Walther P99s for handguns and double daggers for melee. Like Aria, she has earned the title of "Quadra". Riko is a part of Team Baskerville, who chose the affiliation Dean. Originally a criminal she is also known as the Butei Killer.