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: Tina looked at her schedule. Sentence2: One of her teachers was TBD. Sentence3: She was rather inquisitive about it. Sentence4: So she walked into the door. Sentence5: Tina saw a her old teacher actually come back.
Teacher, Tina, Teachers