Suspects:Hisayoshi Minamizawa, Takako Fujii, and Hiroshi Iino
Kogoro, Conan, Ran, and some of Kogoro's friends are at a Mah Jong hall. One of his friends leave so now they're missing a player. They call Hida who says he'll be there in half an hour. He doesn't show so the gang goes to investigate. They run into Minamizawa who says he forgot his cell phone. They go to check on Hida who's dead. He suffocated because of potassium cyanide poisoning. The room was locked doors and windows.
Hida's right thumb was poisoned when he went to turn off a burner that the killer had turned on. The switch on the burner had poison on it which rubbed off on his thumb. When he returned to count his bills he locked the doors and windows. The killer knew that Hida licked his finger to separate the bills so that was how Hida poisoned himself. The killer was Takako Fujii. When the police came, Takako used bleach to wipe the burner switch clean and Conan used iodine to prove that her handkerchief was soaked in bleach. Her boyfriend had borrowed money from Hida but couldn't pay it back so he hung himself. He took the loan so that Takako could have a heart operation. She worked for Hida in order to plan her revenge and kill him.
