Anon kept a pair of yukkuri in his house, a Reimu and Marisa.
He lost his pet Chen and then on his way, he picked up a pair of yukkuri babies who's crying for human to take them as pet.
This sisters of Reimu and Marisa had a unique history. They're born as stray and got taken by human once. There, they are taught many things to become pet, but they failed and got thrown out again.
Now they have bronze badge, but Anon promised if they can get gold badge, or at least silver badge, he would take care of them even if they turns into scum. Reimu and Marisa grow into adult well, but they failed one thing.
They refreshed and have babies. This made Anon angry because he will surely let them have babies after they get their badge. This pair can't even hold themselves for a while.
Marisa and Reimu promised to raise their little ones into great yukkuri. They don't want to be stray anymore. Apparently, being stray twice has traumatized them.
Although not putting much expectation, Anon throw them into his garden and will give them food twice a day. If they managed to raise a great child, then he will consider taking them back into the house.
He felt that he did take these two as pets, so he will not be irresponsible and just throw them away.
Just then, his friend called and offered a baby yukkuri. He had a newborn baby Chen without master yet. This baby is from good lineage and has done all the training as well as getting silver badge. Chen also could easily pass gold badge test.
Anon loves this Chen. Both take it easy in the house while Marisa and Reimu watch jealously.
The only thing they have that Chen doesn't is a companion. Using that, they kept verbally abusing Chen with her loneliness.
One night, Anon heard Chen said she's lonely in her sleep, so he bought a Ran as companion as well as to teach Chen to pass the gold badge test. Ran protected Chen.
Marisa and Reimu remember Ran's eyes, the eyes of pet yukkuri who look down on them when they're still stray babies. It's a painful trauma and they tried avoiding Ran as much as they can.
Then, their only expectation. Their babies will soon be born. They can take it easy with the babies and if the children are good, they will be taken back into the house.
They also know Ran and Chen must have been told by Mister to not get Refreshed so they will not have babies.
Sadly, Marisa and Reimu's babies are "lacking". Small volume of hair, small accessories, can't speak, can't understand speech, they can't even control their pee pee and poo poo. Teaching these children are impossible, Reimu and Marisa understand that. But if they kill the babies, not only they would get punished by Mister, they will also be hated by other yukkuri as killers.
There's some possible reasons. Reimu and Marisa are sisters, maybe incest is also bad for yukkuri. Reimu and Marisa is not feed well, never feeling full and live in uneasyness. In hope that the children will soon let them take it easy, the parents hurried their children to be born. Either way, these children are lacking as a yukkuri.
In the other hand, Chen has received her gold badge and allowed to have babies. Unlike Reimu, Chen is having mammalian birth of the easy yukkuri.
Their child is a Chen who's smart like her parents. Even as a baby, she almost doesn't have any slurring in her speech.
Reimu and Marisa has gave up on their baby. They only feed the baby while jealously looking the easy life inside. Same with their babies, who despite being yukkuri, they're filled with jealousy and hate, never knowing what easyness means.
When they grow big enough, they go and slammed on the window glass, scaring Chen's child.
Fearing they will be thrown out to the street, Reimu and Marisa jump and killed their own children. Their life now is better, at least they don't have to worry about food. They are not going back to the street.
The murder traumatized Chen's daughter. Anon then kept Reimu and Marisa in a tight transparent box, feeding them just enough to keep them alive. Both yukkuri can't move and can only watch and listen to the family living happily.
One day, they just died of age. Their last words are dry "want to take it easy more" of yukkuri living in despair. They had stopped thinking of where everything went wrong.
To analyze this, the first misfortune for Reimu and Marisa is to meet Anon. He picked them as pet just because of momentary grief of losing his pet and half-assed love. That's fine, but he's also a hypocrite who insist on keeping the pair in the name of "responsibility". If he would just throw them out to the street, at least Reimu and Marisa won't live so long in despair, they can have another different fate.
The next misfortune is Chen. Anon loves Chen types, and after getting the baby, he totally lost interest in Reimu and Marisa. Because of this, he never paid attention to them anymore.
Then there's also the babies.
But Reimu and Marisa is wrong for not able to hold back a little more. If they get their badge, they would be able to have babies. Anon also promised he will take care of them no matter what after that. But with a poor excuse, Reimu and Marisa made children on their own.
Either way, they have to end their uneasy life in a small transparent box, unable to move and watching joy they can never have ever.
When Anon found the two dead yukkuri, he just throw them away. His face is the expression of a man liberated from a great burden.