Sense Abel is the Stage 4 boss of eXceed - Gun Bullet Children. She is a vampire going by the nickname of the "Blue Moon Siren" as she is capable of killing enemies with her singing. She is the Undead Lord's top enforcer.
Sense has the capability of converting sound into magic, which earned her the right to be dubbed the "Blue Moon Siren" as her singing voice brings victory to her allies and death to her opponents. She is in fact over 1,000 years old and is a descendant of a renowned bloodline of vampires. Her qualities earn her a place as the most trusted lieutenant of the Undead Lord, the leader of the vampires.