The Sohma curse has a pretty dark origin story. Basically, there was this lonely figure—the first god of the Chinese zodiac—who managed to befriend thirteen animals. These animals saw them as a god, and the god got so attached that they couldn't bear to lose them. So they cast a spell to lock everyone into an eternal cycle together, binding themselves and the animals across all their future lives. That binding is what created the Sohma family curse we know today.
Content compiled by AnimeList.moe from publicly available sources.
