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すべて忘れてしまうから
以撰写推理作品维生的作家“M”（阿部宽）有一位交往了5年的恋人“F”。因为刚好遇上截稿日，M无意中没与F联络，就这样过了3週，在M经常去的“灯塔酒吧”出现一位自称是F姐姐的女性（酒井美纪），她说F从万圣节的那晚就失联且行踪不明。 “涩谷站人很多，我会晚到” M和F的姐姐收到这则内容相同的讯息，促使他开始寻找F。但在过程中遇见的每个人口中的那个她，却都不是M所认识的“F”。 M原本觉得即使生活一成不变也无所谓，每天都过得还算开心。然而他在寻找F的过程中，被牵扯进那些想要改变的人们的琐碎问题中，逐渐察觉日常平稳变化，可悲却惹人怜爱、探讨人性的连续剧即将上演。
推理作家的“M”得知恋人的“F”自从万圣节的晚上就行踪不明。当他苦恼著是否要接下不擅长的散文连载委託时，他被突然出现的F的姐姐逼问女友的所在处。
M visits his girlfriend's workplace, a kindergarten, to find clues to her whereabouts.
M creates his first social media account, and receives his first online threat.
It is past midnight at BAR Lighthouse and only M, a beautiful woman, and Izumi are left.
M spends New Year's at home when he gets a call from his missing girlfriend.
M's life continues to slowly and surely change.
After suddenly going missing one day, F's story is now finally revealed.
M is tasked with looking after a cat and Fukuo reveals a huge secret.
M and F reunite and decide to take a trip. M enjoys himself, but F realizes that she has changed.
One year has passed. People are moving on, and M finds the right way to finish his essays.
