Message from Hazy: This is honestly all the background you need to join the site. The idea of the storyline isn't complicated in itself, the complication comes from the complex relationships between characters.
Without further ado:
Honda Tohru is a young girl in high school who recently lost her mother, Kyoko, in a car accident. As a result, Tohru was forced to go live with her grandfather (her dad’s father). While he was pleased to see her, he was merely a old man living off of his life savings, and thusly Tohru promised that she would pay her own tuition and expenses by working, so that she would not be a burden to him. However, later, they would have to move in with his daughter’s family, who wasn’t exactly keen on the idea of having Tohru around. Nonetheless, the began to prepare renovations on their home in preparation for having more people live there. During this time it was asked that Tohru go live with some friends until the renovations were complete. Not wanting to be a burden on any of her friends, Tohru pitched a tent in some nearby woods and began living on her own.
One day, about a week and a half after she initially started living in the tent, Tohru came upon a house in the woods that she had never seen before. There were little snacks in the shape of the Juunishi, or the twelve animals of the Chinese zodiac. When she went for further inspection, a man came out, who would later be identified as Shigure Sohma. They began discussing the folktale of the Chinese zodiac. Tohru explained that she would always cry at the story as a child, because she adored the cat of the story most of all. Shigure found this utterly amusing, yet fascinating.
Later that same day, Yuki and Shigure were walking through the woods, discussing the dynamics of needing a woman around the house, when they stumbled upon a feverish Tohru and her tent. They took her back to their house, where she explained about the tent and why she was living there. It would be suggested by Yuki the next morning that she begin living with them until things were all fixed with her family’s home. This was how she would come to meet Kyou and discover his dislike for Yuki and Yuki’s dislike for him. Through a twist in fate, she would discover exactly why they hated each other so much: members of the Sohma family are cursed with the vengeful spirits of the Juunishi and whenever they are hugged by members of the opposite sex or are nervous or sick, they turn into the animal they are cursed with. After awhile they will return to normal, but this varies on the person and why they transformed to begin with. Kyou was cursed with the cat, Yuki with the rat, and Shigure with the dog.
No outsiders are supposed to know this secret, however. In fact, the ones that do find out have their memories erased by another member of the mysterious Sohma family. Akito, the head of the Sohma family, allows Tohru to keep her memories and live with the Kyou, Yuki, and Shigure. Eventually she begins to meet the other cursed Sohma’s, developing close bonds with them as well…
The series focuses on the effect that Tohru has on the people of the Souma family that come in contact with her, as well as her life and the hardships that she goes through. But on top of all is the secret of the Souma family's curse. Is there a way to heal it? Will Tohru be the one to do so? Or will her heart and everyone else's who got in contact with her be broken in the end, like many before her? The Souma family is very dark and very secretive. Tohru is warned on a few occasions to not get involved, but it seems she's too deeply involved already.
Shameless Plug: It’s a beautiful manga/anime. Though this is all the knowledge you really need to join the site, I’d suggest everyone read it. There’s even a site that does scans of the manga for free. Just ask and I’ll be more than happy to point you towards it.