Shibuki (a ninja girl)
Uses the archaic pronoun sessha, which immediately indicates that she's a ninja.
Caitlin, Honey, and Lustat
Use the more feminized version of the standard pronoun watashi—atashi.
Odango (a robot rice cooker)
Uses watashi, but with a writing error (ワタシ instead of 私), to show that she's a robot.
Suzu (a fox)
Uses the pronoun warawa, which emphasizes that she's an ancient Japanese spirit.
Tessa (a dog girl)
Uses boku, the standard pronoun for children—in Japan animals are often referred to as kids.