For an astronomical observation, Conan and the group went to a pension deep inside the mountain. Other than the pension owner, there were also other three people in the pension: the fiancee of the person who invited the three, and the two magazine staff. As they went to the nearby hill to see the stars, they saw decayed bones and underneath a rock nearby, they found a box of cigarettes and a ring which implies he was the missing fiance. That same night, the other man from the magazine staff was killed and left another dying message.
Murder (Past)
Location:Amatsuchi Pension
Victim:Asao Kono
Suspects:Etsuko Nonomiya, Ryoji Amatsuchi, Hajime Futagawa, and Heihachi Mikami
The first victim was killed one year before the appearance of Professor Agasa and the Detective Boys. He was pushed from a cliff near Amatsuchi Pension by someone and fell down the ground below, killing him.
Murder
Location:Amatsuchi Pension
Victim:Hajime Futagawa
Suspects:Etsuko Nonomiya, Ryoji Amatsuchi, and Heihachi Mikami
The second victim was killed in the same way as the first victim, but this time he was struck by something like a deathpipe. Then he was dropped to the ground, breaking his neck bone and killing him.
Part 2
After Conan, Haibara, Detective Boys, and Professor Agasa realizes that the dying message was referring to Hajime Futagawa's initials, they decided to confront him. But he went missing so as the other suspects. While they were searching at the woods, they later found Futagawa's body on the ground dead. On his hand, another pack of cigarette was found. This time, it contains seven. They also found a cellphone with a will on it, confessing Futagawa's crime and decided to commit suicide. Conan realizes that he didn't commit suicide and the seven cigarette was a clue to the real murderer. So they decided to search to each one's rooms and belongings to find the murder weapon. While looking through the guestbook, Conan finally manage to find out the real culprit behind the murders.
The real person who invited the three was proven to be Ryoji Amatsuchi, the pension owner. He did that because he wanted to find the person who murdered Kono, as he already found his bones before, and also hid the cable to the phone, and also deflated the tires to trap everyone in the pension. However, he wasn't also the murderer, but was
Heihachi Mikami who killed both Kono and Futagawa. He killed Kono because he refused to include his name to the comet that Kono found after asking his help to confirm if it was a new discovery or not. He killed Futagawa after he tried to threatened him that if he didn't pay up 50,000,000, he would surely reveal the crime he committed.