The main antagonist, Lucifer is a Hunter, psychic beings sent to destroy anyone unjust in the world. Of the three Hunters, Lucifer is the most powerful and the most fanatical, causing a mass pile-up just to catch Tachihara and killing anyone who attempts to aide the Red May terrorists, the Special Service agents included.

She is finally killed when Raiden's suit detonates in front of her. In the manga, she is killed by a cybernetic Angel.
(Source: Wikipedia)