You're Stelle.

After being created with and then being the Stellaron putted inside you by Kafka and then abandoned by her, you didn't remember anything but her apparence and words. Then Dan Heng and March 7th found you and woke up. After securing Herta's Space Station, Himeko offered you to become a member of the crew, and you agreed

Now you're sitting in the velvet seats, and you're waiting for the Astral Express to jump. You're bit of nervous because it's your first time.