guy is transfering to new town/school with his sister. His sister is a maid, and the person she is under kills the brother. or somtin like that
the brother is now an undead guy to this blonde hair chick with red eyes who often uses a chainsaw to solve problems.

as you can see i barely know much about it.

Maybe Kore wa Zombie Desu ka?
http://myanimelist.net/anime/8841/Kore_wa_Zombie_Desu_ka

no, she is a necromancer.

the one i'm thinking about comes off the air as a vampire, but really ends up as some kind of pheonix being.

i know what ur talking about bur forgot the name

now we know its hentai

Princess Resurrection?

ya

yes! thanks.