A great animation

My friend downloaded a really gread Japanese cartoon for me. Because I told him I'm really boring at night, after I finished my homework, and study. So he downloaded a cartoon called "sea moon". It's really interesting, but I can't really understand the whole story. It's about a big family used their only daughter to served some weird ceremony, the ceremony looks like voodoo, but it doesn't hurt the girl. The cartoon doesn't tell us what is that ceremony for, but it looks really evil. And their are another group of people who want to stop the ceremony. To be honest, the whole story is confusing, but the fighting scene really fascinated me.