How can blood from one victim, murdered on the street, wind up on the wall of an abandoned building, the railing of a rooftop, and broken glass of an upper apartment window? This is the question Conan must answer if he is to catch a crafty killer entrenched in a seemingly innocent mountain-climbing fraternity, which hides a deadly secret!
Kouji Takeno was the killer. His reason was that both he and Ikuta were in love with the same woman, Keiko Togawa, but she died in a hiking incident where the group had to leave her in the mountains to search for help and couldn't return in time to save her from freezing to death. Later, Takeno found out that Ikuta messed up with the group in purpose to have the unfortunate Keiko dead since she rejected his affections in favor of Takeno's; Ikuta was actually bragging about it while drunkenly rambling to the also drunk Nakamura.
The weapon of choice was actually Takeno's socks, which are very resistent special socks used by sportsmen and specially by hikers. He easily filled them with lots of small rocks he got from an aquarium, since they wouldn't break; once he built a VERY hard and heavy "weapon", which would easily kill a person if used to hit them, Takeno put the used some fishing rope to tie everything up, and then launch it towards Ikuta, who was merely standing in the street while smoking.
Ikuta was a heavy smoker, so Takeno could easily see his lit cigarette and pinpoint his improvised "sock full of rocks" towards him; the blood in the different buildings came from the "sack" bouncing on them due to the full strenght of the impact. The proof came when some strands of wool coming from the socks were found in the aquarium: Takeno returned the rocks to their original place but the tiny strands remained, and they had Ikuta's DNA on them.
