Conan explains it would be impossible to always have a shirt bought on 12:28 for all thirteen days and reveals the sender to be the cashier, Mai Seta. Seta reveals that the bomber murdered her father thirteen years ago in order to hide the fact he was embezzling money from her father's company. Conan reveals that the shirts creases are flag signals conveying the message "I saw you burying it". The bomber denies the murder until Conan discloses that the body must be near the cabin since the bomber was a novice at mountaineering. The bomber confesses and explains he wanted the best for his son to stop him from running away from home. Seta asks Conan how he knew it was related to the mountains to which Kogoro answers by reading the deductions he received from a cellphone text message. Conan and Ran trace the call to a man who explains he did not send the message and reveals a man resembling Akai was the one who gave him the phone.