Reimu is a bronze-bagde Yukkuri that was meant to be shipped to the Factory, but on the very last day a Big sis brought her as a pet. Big sis and her family treat her with love and Reimu does the same.
One day when Big sis took her out for a walk, she meet and fall in love with a stray Marisa. Marisa isn't a scum and very afraid of human, she know she cannot be together with a pet Yukkuri but it can't be helped since they both very much in love with each other. Later Reimu got pregant and told Marisa she want to reveal it to Big Sis, but Marisa said it's better to hide and give birth in sercret instead, so Reimu (reluctantly) agree. Not soon after, Big sis's father got a promotion and they must move to another place. When Reimu heard about that she got angry and decided to break the news to the family that she pregant and want Marisa to move in. Naturally she got kick out of the house. After a night of begging she accepct the her family didn't want her back and went to Marisa's place, which they got married and stay together.
Reimu is unable to adapted to a lives of a stray so Marisa doing her best to make her comformable, which she manage to give birth to 3 heathly koyukkuri (these strips). Despite Reimu doing her part to help, Marisa was unaable to provide for her family so she have to break into human garden to find food. One days while hunting for food in another house, Marisa got captured and beat up. Reimu rush to apologize to the man only to realize he is Big sis's dad. The dad didn't recognize her at first, but then he saw Reimu's bagde with his daughter's name on it he got angry, saying Big Sis and his wife miss her and it took him a lots of effort to make them smile again so he didn't want them to meet Reimu. The dad then kill Marisa and throw Reimu away
Reimu run away and in shock, both from the fact the human she call Dad kill Marisa and that he only recognize her due to her badge. More horrible news come when she arrive home: her children has been killed by a mister Mohawk, with only a KoMarisa as a survivor. Lucky for them a group of stray yukkuri whose Marisa once belonged to, led by a Patchouli, taken them in their herd. Due to her status as a ex-pet Yukkuriand also she the wife of the most easy Marisa in the herd, most of the other Yukkuri treat her harshly which cause her to remind of the day when she was with Big sis. This became worse when the herd found of that Marisa got killed while broken in a human house. They believed it was Reimu fault since she can't eat trash like a stray. They kick her and the KoMarisa out. Reimu became livid, often dreaming about her days as a pet while strugling to find food. Eventually she and her child got caught by Fatory's Extreminator and his Remilla. Reimu found out that the Extreminator is actually Bis sis's Dad, and this is his new job. KoMarisa got eaten while Reimu running back to the herd. This help the dad find out the herd location and called other Extreminator to get rid of it.
In the end, Reimu and the whole herd got capture to the Factory, and Reimu herself scream in despair as her happy memory(paste) got suck out