Note: The Minami Takayama mentioned here is the Minami Takayama who voices Conan! TWO-MIX is a popular j-pop group.

From Shonen Sunday magazine...

A popular group whose new songs always becomes one of the Top 10, "TWO-MIX"'s Minami Takayama and Shiina Nagano are kidnapped in front of Conan and the Detective Boys! The reason being a demo version of a new TWO-MIX song that was played on the radio and the demand for Conan and friend to hold the tape... It's the Detective Boy's most active time!