A wild komarisa, Maricha, was on a little adventure, and was distracted by the pleasant ringing of a bell. She went after the source and in the corner of a small cave found what appeared to be a very, very easy yukkuri, wearing a very easy smile and donning a specially easy okurumi (sweater).
Maricha cannot help herself but to rub rub with it, then went home soon afterward.
The next morning, Maricha woke up with a very easy sweater on her body, much to her parents' surprise. Maricha immediately declared she got this because she is very easy, and it is the gift from god for easy yukkuris. Everyone in the herd saw Maricha with admiration, except herd leader wise Pache.
Herd leader wise Pache tried to warn everyone that the greenstuff isn't easy mister sweater but something that would make everyone not take it easy, but no yu believes in her, insisted it's easy mister sweater, then collectively punished her(hence the eyepatch) and locked her up. Everyone then decided it's a good idea to rub rub with the easy Maricha.
The next few days, everyone in the herd began growing the easy sweater as well, and every yu is happy. All is well until Maricha woke up one day and suddenly felt her body itching all over.
They went to Pache demanding for answers, but was greeted with the revelation about the mold-okurumi-damashi (lying sweater), and that everyone who has it is royally f*cked. Maricha wanted to punish Pache, but upon hopping to do a body slam Maricha realized she can no longer control her body.
As it turned out, once the mold penetrated the skin, it takes hold of the motor portion of the core paste, controlling its host like cordicep in insects. In this vein, Maricha began venturing out of the herd and deep into the forest, all the while suffering the unbearable itch as the mold grew into her skin. Maricha prayed for a quick death by the fangs of Remilia, but even Remis have the innate intuition to know that the 'sweater' isn't to be trifled with, and left Maricha to her fate.
Once reaching a suitable spot, the mold then creates a small tear on the bottom of Maricha's footsies, allowing ants to enter and eat Maricha from the inside out, transporting the spore-filled paste elsewhere. The mold also caused the skin to harden, causing Maricha's face to be fixated into a seemingly easy 'smile'. With only her skin and paste core left intact, Maricha suffered an excruciating death.
What finally became of Maricha was exactly what she found in the forest that day- an easy seeming yukkuri in a very easy sweater, giving off 'pleasant ringings' as the dried up paste core rolled inside the hollow, hardened husk, attracting the next victim.