This is a yukkuri clan in a safe forest. There's no predator and yukkuri live their days by doing specific jobs. Reimu type take care of the babies while Marisa went to hunt and Alice build their nests. The only exception is when a yukkuri is giving birth. That time, the whole family take a rest and watch the birth.
Marisa and Reimu is having their first litter of baby yukkuri. It's a mammalian pregnancy. First daughter is a very easy Reimu. Second daughter is a Marisa who can already say "being born da je" when born, making her father proud. But the last one is a defect who can't speak.
Father Marisa hate this youngest baby. While her elder sisters get happyness! food, the youngest Marisa is given bitter grass. Reimu cared for her youngest child, but Marisa stopped her.
Late at night, the elder Marisa gave her sister food without telling their father. As they grow to KoYukkuri, the elder Marisa finally told the youngest Marisa that food grow by itself inside the nest because they're very easy. Youngest Marisa doesn't believe that. She know everyone never replied her greeting and never say she's easy. Even if the food grow out by itself, it's not hers. She also noticed that her mother is getting thinner although she should be eating a lot.
One day, elder sister Marisa is gone. There has been cases of disappearing KoMarisa so the clan suspect this is raper's work, but they can't catch the suspect. Father Marisa's friend found sister Marisa by the river, already dead.
In grief, father Marisa bring sister Marisa home. The youngest Marisa loved her sister, the only one in the world who's kind to her. This is no longer love as a sister. Father Marisa can't accept the death of her loved child. She blamed it on the youngest Marisa. When Reimu tried to protect her child, Marisa finally told her family what she found. Mother Reimu never take her husband to meet her family. That's because Reimu's family is filled with defect yukkuri. It runs in the family. Father Marisa then stabbed her own wife to "take out the bad paste".
Little Marisa run away from home, until she almost collapsed. She's still traumatized by the bitter grass her father gave her as first meal that she couldn't eat it despite growing big enough to be able to at least force herself to eat.
She's then found by an Alice who takes her and feed her. For once, Marisa felt glad, but all is lost when Alice keep licking on her. This is a raper.
Marisa almost die, but she's saved by a Patchouli who killed the raper with stone. Patchouli understand Marisa's incomprehensible words and healed her. She also give Marisa medicine that helped her to slowly be able to speak, although still not perfect.
With Patchouli's love, Marisa feel happyness in her life and learned a lot. Even still a child, she can hunt as good as adults already. Patchouli also taught her how to read human language, something that even pet shop koyukkuri wouldn't be able to do.
One day, Marisa went home from hunting. Patchouli is still making medicine in their home, so Marisa want to go home as soon as possible and take it easy together. She also found a "magic tome", piece of paper with human letters she can read and can't read. This will be present for Patchouli.
What she found instead is the dead body of Patchouli. A human tortured Patchouli and then Marisa.
For a while, he explained what happened.
The small river flowing near Patchouli's home is river of death for yukkuri. This is the answer to Marisa's question on why Patchouli never allowed her to drink water from Mister River.
Upstream are laboratories and factory built by yukkuri lover organization Yukkurinpeace. They want to create yukkuri medicine stronger than orange juice. This medicine will heal even mould, burns and anti-yukkuritis.
Ironically, the waste material they throw to the river is becoming poison only for yukkuri. They made the drugs from natural material, so nobody expected it would be poisonous. The poison also has no effect on any creatures, which make everyone realize it even less.
But mountain climbers noticed. The poison caused birth defects. Marisa is one of them. The man torturing her has been researching the poison for a while. To keep the research hidden from Yukkurinpeace, he also abuse and kill random yukkuri to make it seems like the usual abyuse. One of the victims are Marisa's sister who even then, still tried hard to return home to her younger sister at home.
Now, the research is completed. Yukkurinpeace should know soon about the poison they made, and to protect themselves, they will most likely clean the mess by killing all the yukkuri in the forest. If that happen, the man is happy because he will get even more chance to destroy yukkuri and the yukkuri lovers.
Before they go, he injected Marisa with concentrate of the river's poison right to Marisa's paste core.
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Back in the clan, father Marisa is thrown to the river as punishment for trying to kill her own wife.
KoReimu who's not hurt too much starts going out to hunt for her mother. Today, he went to the usual hunting ground and saw a really sad man. Just as KoReimu is about to sing for this man, she's crushed. He's from the Yukkurinpeace, saying they can't end in place like this.
Next day, there's no sound of happyness from the clan.