Mystery Night! / Eighteen Emotion (ミステリーナイト！／エイティーン エモーション) is S/mileage's 16th major single. It was released on April 30, 2014 in 5 editions: 2 regular and 3 limited editions. The first press of the regular editions came with a random trading card of 7 kinds depending on the jackets (14 in total). The limited editions came with an event lottery serial number card.