Conan, Kogoro, and Ran are driving to a hot spring when the road gets closed due to snow, and so they accept an offer of staying the night at a nearby house, where they meet Yoshiro Daimon, a famous guitarist, Kazuki Daimon, his brother, Hatsuho Hojo, their housekeeper, Kayoko Daimon, Kazuki's wife, Genichiro Daimon, Daimon Industries President, and Tatsuko Daimon, his wife. The next day they discover the body of the company president dead.
Murder
Location:Daimon household: Separate room from the residence
Victim:Genichiro Daimon
Cause of death:Stab wound
Suspects:Yoshiro Daimon, Hatsuho Hojo, Kayoko Daimon, and Tatsuko Daimon
When they follow the footprints, they find his eldest son dressed up in armor and also dead in a locked room.
Murder
Location:Daimon household: Audio Room
Victim:Kazuki Daimon
Cause of death:Stab wound
Suspects:Yoshiro Daimon, Hatsuho Hojo, Kayoko Daimon, and Tatsuko Daimon
The company president's wife declares that they were killed by the spirit of a 500 year old samurai whose death anniversary was that day.
Part 2
Conan discovers that the footprints of the armor in the snow were used to cover up the culprit's footprints, and finds that the locked room the son died in was set up.
Conan stuns Kogoro and said that on Genichiro's murder, the culprit attempt to cover his tracks with the footprint technique he explained earlier, but in that case anyone other than Tatsuko, who saw the armor could have done it. Most likely, after killing Genichiro, the culprit was splattered with blood. However, neither the armor nor Kazuki's clothes have been stained. After the culprit killed Genichiro, they came into the audio room and killed Kazuki. Recalling the katana lying on the floor in the audio room. When they first saw it, they jumped to the conclusion that it was used only as the weapon but however the katana wasn't just a weapon it had another particularly sneaky purpose to turn the audio room into a locked room. After the culprit killed Kazuki, they dressed him in the armor then stabbed the katana into the wall near the door. Then, with the other end of the katana they rested it upon the door handle slowly but surely exited the room without letting the katana fall and used the force of the closing door to make the katana bolt the lock with this the sealed room was complete. they knew that no one would have the strength to open the dead-bolted door and they also knew that trying to break the door down would cause the katana to fall to the floor, leaving the trick would unexposed or so the culprit thought. Before that, they must analyze the significance of the case happening on the anniversary of Hidetomi's death, the culprit took advantage of the legend and left those large footprints to make it seem as though the only possible culprit was the armored warrior this fooled them into believing Kazuki killed Genichiro and committed suicide shortly thereafter to make this more believable, the culprit purposely directed Tatsuko who strongly believed in the legend, to bear witness to the animated suit of armor being the anniversary of Hidetomi's death, everyone knew that Tatsuko would be praying at the altar at exactly 12:00 AM, and dclares Hatsuho Hojo to be the culprit. After that he shows a picture that shows Hatsuho and his father that it was revealed that it was the CEO who comitted suicide.
Hojo confesses and reveals his father, who owned his own company, cherished human relations over cruel business deals he accepted unreasonable orderes from Daimon Industries with a smile, since they had been trading partners for ages. However, with just on mistake, their transactions with Daimon Industries ceased and the factory went bankrupt. Daimon Industries overcame their financial difficulty by cutting off her father's factory as if to deal the final blow to my father, Genichiro stole their family heirloom, the armor from him he sold their armor to raise money to pay his employees. He couldn't do anything for his workers, and he had lost a big part of their family's history. he blamed himself for it all, and committed suicide. When she was working in Tokyo she changed her name and began to live on Genichiro's house so that she could absolve her father of his regret and so that she could have her revenge on the anniversary of her father's death.
