Given the task definition and input, reply with output. In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.

Sentence1: Billy Bully was a detective. Sentence2: At night was when he liked to case his projects. Sentence3: One evening while on a stakeout, one of his marks made him. Sentence4: Billy tried to speed away as gunfire peppered his car. Sentence5: Luckily for Billy his glass was bulletproof.
Billy