An aspiring author struggles to get published and witnesses a little girl get run over by a truck. What surprises him the most is the unusual reaction of her friend, who carefully saves the game she was playing before running towards her dead friend screaming. A few days later, as he was riding his bike to his university, his bike came to a sudden stop and he got ejected. The culprit was a recorder that somehow got stuck in his back wheel. Later that day, he noticed he had lost the key to his house and called a locksmith to change the lock. When he sat down at his desk, the young girl he had seen a few days earlier (referred to as U.U.) was hiding and abducted him by menacing him with a knife. She led him to her house and trapped him in a closet to prevent him from revealing her secret to anyone. Realizing he had a phone, he hesitated but decided against calling the police. He instead decided to wait until her parents came home, which never happened. The next day, the girl greeted him and left for school as he realized he was starting to be famished and dehydrated. As the girl came home from school, she presented him with poorly packaged food that looked like a school lunch. He started eating when she started yelling at him to properly thank for the food before eating, leading him to realize how obsessed she was with formalities.

The following day, after the girl left for school, his urgent need to use the bathroom pushed him to get out of the closet as he realized he could simply lift the whole door up and take it off its rails. Instead of escaping, he decided to take a look at the house. This is when it hit him that a little girl couldn’t possibly live all by herself in such a big house, and the state of the house (messy, with piles of objects everywhere, a dry sink and an empty fridge) was a testament to this fact. This meant that the food she had given him the day before was actually her own school lunch she had given up to allow him to eat. When she came back home and offered him food again, he convinced her to eat it together with her. After that, he asked about her parents, to which she replied that they had gone away.

The next day being a Saturday, the girl wouldn’t be going to school so the man wouldn’t be able to take a look at the house. He decided to hand her a 10,000 yen bill and ask her to go buy food at a grocery store. After she came back, he offered her to eat some of the food but she refused, seemingly due to one of her self-imposed rules. The next day, after eating together, the girl realized the man smelled and got him to take a bath, at which point he realized her whole body was covered with bruises and wounds.

On Monday, the girl left for school again and the man decided to clean the house, then finally take a look at her room on the second floor. That’s where he found an old notebook filled with rules written by an adult. These rules where the ones the girl had been strictly following since her parents had gone away, and they explained her actions on the day of the accident: the rule to never leave her games running when she wasn’t playing them was before the one to value her friends. This meant her parents were the ones at fault for her bad education, and had never admitted their mistake. Then, in their room. the man found the corpses of both parents choking each other to death. As for the girl, everything was starting to crumble around her at school, with teachers asking her question she couldn’t answer because of her rules, creating a huge internal dilemma in her mind. When coming back home, she fell asleep in the arms of the man who was waiting for her. He carried her in the living room and asked her how he could help her, despite feeling like there wasn’t anything he could do for her anyway. She asked him to tell her a story like her parents used to, making him realize there actually was one thing he could do, as an aspiring author. He then proceeded to tell him about stories about characters that may have gone off the right path and dropped out of society, but still managed to live lives reasonably fun and interesting.

The next day, alerted by someone who thought the girl’s actions outside the home were odd, the police showed up and took them both into custody. The man was questioned by the police for a while before being released after many testimonies cleared him of all suspicions. He went on to become an author, whose stories were nothing but extensions of the ones he told the girl that one night. One day, he got a meeting with a new editor replacing his former one. That editor was a young girl called Yuu Yuugure, who presented herself as a fan of his works ever since he was a child and was hoping to hear a lot of fun and exciting stories from him. The story ends as it started between them, with the man simply saying “nice to meet you” to the girl.