Friendship Washed Away In The Riverbed Kogoro, Ran and Conan went to a traditional ryokan to enjoy the day. They meet 3 college girls who came to take photograph. Conan notices the water mill isn't working and the staff say that it has been converted into an ice house. After taking some photos, the three girls left for various reasons. Ran and Conan were about to enjoy some shaved ice when they notice the river turning red. Akiba Yuko was found dead, floating in the river with red flowers on her. Conan reveals those flowers are a fern called Azolla Japonica that grows in lakes. From the victim's phone, the police believed that she could have accidentally fallen when trying to take a photo. However, Conan thinks that it is not an accident but murder. He begins to investigate and find the true culprit.