Kogoro is invited by a female fan named Toyoko to visit her monja restaurant with Conan. Kogoro is shocked to discover that Toyoko is an old woman who looks nothing like her photo. While eating monja, Toyoko chokes and spits out a cabbage core. She claims someone put the core in the monja in an attempt to take her life. Toyoko suspects the culprit is one of her three childhood friends Eiko, Kyoko, or Yuko. Kogoro is hired to talked to the three women, and all three of them seem to resent Toyoko..