nope riku was definitly beyond saving.

There was an episode before where joel places a drop of saya's blood into a petri dish of diva's blood and it just crystalized...so basically if their blood comes into contact with each other at all then it's game over...

lol i agree with masamuneehs, if this doesn't turn kai into a bloodthirsty chiropteran hunter then i don't know what will..=)