While on their way to school, the Detective Boys help Ayumi decide what to write in her illustrated diary. Everyone offers their own advice, including Conan, who tells her she'll find something to write about by closely observing her surroundings. Meanwhile, a small crowd has gathered around Jewelry Kaneko's shop window to admire the luxury watch on display. Though it's thoroughly protected by security systems, the drawings in Ayumi's illustrated diary lead Conan to believe that a thief is attemping to steal the watch...