Keita Amano's ordinary elementary school routine is upended when he discovers a capsule machine on his way to school. After opening a capsule-shaped rock from the machine, Keita releases the youkai Whisper, who expresses his gratitude and declares himself Keita's personal butler from that point on. Whisper also gives Keita the Youkai Watch, a device that enables its user to see and form contracts with the youkai in their surroundings. Soon, Keita encounters a wide variety of youkai causing chaos in his daily life. With the assistance of Whisper and his expanding roster of supernatural friends, Keita starts to repair the relationship between humanity and the youkai, all without realizing it.