One night, Kazuki Muto jumps in to try to save what he thinks is a girl in distress from a monster and instead gets impaled through the heart. The girl, Tokiko, is actually an alchemic warrior with a Busou Renkin, name of Valkerie Skirt, with the mission to exterminate Homunculi. She implants the only other successful work of alchemy than the Homunculus, the Kakugane, to take the place of Kazuki's heart. The Kakugane resonates with his fighting spirit and forms a Busou Renkin (in his case a spear) so he can fight the Homunculus monsters who prey on humans. Kazuki joins with Tokiko to battle with the Homunculi and protect his friends and his sister Mahiro.
It appears that this is a very worth watching anime. The idea might not seams cool bu it delivers very nicely.
It has an awesome story, got me going right from the start.
The story is about how the main character dies and is revived with the help of alchemy, but once that he found out about alchemy he can never go back to his normal life. He starts fighting to protect himself and family/friends. Soon after some trials he is pitted against an undefeatable enemy finds out that he is not your usual alchemist.
Can't fink of any bad points for this anime, it has been some time since I watched it.
All in all I recommend it to anyone, it's a very nice watch.