Aitsuki is a very ordinary office lady who usually works in Tokyo. However, even though it was an ordinary office lady, during the busy season, the mentality was much more tired than the physical body due to the continuous service overtime. Therefore, I plan to go mountain climbing alone, which is my only hobby. I decided to climb a mountain by collecting information using SNS, thinking that the first place would be good if possible. However, when I actually go there, even those who have experienced mountaineering can easily get lost. Of course, Aitsuki gets lost, but he escapes the difficulty of reaching a certain mountain cottage. But the tragedy started there ... A young man with a decency had been following her all the time from the time he was about to enter the mountain. And an unpopular mountain cottage ... Beginning preparations for perfect crime detention training that the younger man had been warming up.