Prologue: In the wild, yukkuris almost never travel. If they do, it must be because their Easy Place has become uneasy. Something very uneasy happens, so a Marisa leads about three hundred of her fellow clan members to find a new Easy Place. It is a difficult journey, and many yukkuris take it easy forever on the way, but when their numbers have dwindled to about a hundred, at last they find a nice mountainside with plentiful food and water and no predators. Marisa declares it their new Easy Place.
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We begin with various scenes of happy, peaceful clan life. The adults, many of whom lost their own children on the journey, look after the little ones who were orphaned on the journey. They teach them to speak, sing, and hunt; they watch them play and feed them. Leader Marisa and her mate Patchouli--who also lost their children on the journey--watch their clan taking it easy. Marisa is so happy, she is moved to tears.
However, Marisa is still troubled by one incident. Not long after they settled there, they were visited by a delegation of yukkuris from a nearby clan. The visiting leader Patchouli coldly told them there wasn't enough food to support them--that they should leave, or else something uneasy would happen. Marisa interpreted this as a threat, so she gave them one of her mighty puffs, famously able to scare away even a stray dog. The visiting yukkuris were frightened, but their leader Patchouli only said, "I warned you," and then they left. Marisa gets an uneasy feeling whenever she remembers it.
Marisa's mate Patchouli tells her she's overthinking it, that the other tribe only wanted to keep all the food for themselves.
After mealtime, all the children in the clan assemble in front of Marisa. To show their gratitude to their leader, they surprise her with a song--"Easy, Easy, Leader Marisa can take it very easy. Marisa, Marisa, Leader Marisa, Strong and amazing Leader Marisa." Marisa is moved to tears, and swears to herself that she will remember this day as long as she lives.
And she will.
The song is interrupted by the arrival of two humans, a professor and his young assistant. They set up a video camera. Ignoring the yukkuris' increasingly angry protests and demands that they leave, and completely ignoring Marisa's mighty puff, the humans begin grabbing the little ones, scooping both their eyes out with a teaspoon, and setting them back down on the ground. Working swiftly, they've blinded over half the little ones before the shocked adults even realize what's going on and although Marisa's mate Patchouli tells everyone to put the little ones in their mouths and flee, it's too late.
Now the humans start on the adult yukkuris, telling them that if they flee, the helpless little ones won't be able to take it easy. Leader Marisa is still stunned that her puff was ineffective against the humans. She doesn't know what to do, only knows that she can't desert her clan. She sees the humans gouge out Patchouli's eyes, and then she's the last one left.
Watching her desperately lick Patchouli's eyes, the humans are amused by Marisa's sense of responsibility, but their objective is to destroy the clan by making them unable to hunt, and finally, they pick her up and blind her, too.
The clan's hard-won Easy Place has turned into a living hell. To the yukkuris screaming "WHYYYYYYY!?" the humans says it's their hobby, then they take the clan's food stockpile and leave.
The little ones, having eaten just before the humans came, soon have to poop. They poop on themselves and each other, increasing their distress. A father Marisa hears her little ones crying and tries to go to them, but unable to see, she hops right on top of them and crushes them. When she realizes it, she goes mad with grief and hops around wildly, crushing more little ones. She doesn't respond to the other adults' cries at her to stop, so Leader Marisa finally manages to stab her to death with a stick. In the process, Leader Marisa unknowingly crushes the little Reimu who led the song.
Patchouli manages to reach the nest hole where they all live, and she tells the others to follow the sound of her voice, and to crawl, not to hop. The little ones go first, but in pain, blinded, and surrounded by stinking poop and corpses, many of the babies are already throwing up bean paste or in the early stages of antiyukkuritis, and some die before they reach the nest hole. At the nest hole, despairing parents crawl around calling out for their children, but over half of them are dead.
Leader Marisa doesn't know what to do. Blinded, they can't hunt--they can't even go outside because they'll probably be eaten by wild animals. With no other ideas, she tells everyone to go to sleep. They all hope that they'll wake up and find that it was all a bad dream.
The next morning, they're all still blind, miserable, and hungry. Some adults are sent out to bring back food, but they never return--they get lost and fall into the river, or fall off a cliff, or just end up sitting in one spot, too scared to move.
On the second day, the yukkuris are starving and angry. Leader Marisa is half-mad and in denial, insisting that this must all be a bad dream. The others blame her. Patchouli tries to appease them, but they stomp her to death. Her attackers taste her splattered cream and realize it's food. They eat her all up, and this sets off an orgy of cannibalism, yukkuris attacking and biting and eating each other. The frightened little ones call to one of the nursemaid Reimus for help, but she starts eating them too.
Leader Marisa stops crying and gets up to try to stop them, but by then, she's just surrounded by crying, wounded, uneasy yukkuris. She hops around trying to cheer them up, and of course she ends up crushing more of them to death. At last, there's no one left to respond to Marisa. The neighboring leader Patchouli shows up and tells the in-denial Marisa that the entire clan is dead--Marisa's feet are stained with bean paste and custard. Patchouli reminds Marisa that she told her there wasn't enough food for the clan--Patchouli explains that the humans allow her clan to live there with restrictions on refreshing, and that yukkuris who exceed the population limit will be exterminated. Patchouli coldly says she feels sorry for Marisa's clan for falling victim to the professor, but that she warned Marisa.
Marisa attacks Patchouli in a rage, but Patchouli easily avoids her. Patchouli quietly leaves, taking the tiny amount of food remaining in Marisa's clan's stockpile.
Marisa rages, attacking the grass around her, until a cold drop of rain on her cheek returns her to reality. She needs to get back under cover, but she doesn't know which way the nest hole is. Her feet become waterlogged, making her unable to move. The rain soaks her hat and melts her hair. Her soggy skin peels off her head, and then the rain is directly striking her bean paste. Marisa slowly dies screaming in agony and despair while the professor's video camera goes on recording.