Trivia Virtumation, the creator of Tree Yard, stated that her name is Hannah because that's his sister's name. It was confirmed by Virtumation that Hannah is actually The Forgotten Sister of Rareta. In the Early & Alpha Version of Tree Yard, she was referred as Kouhou Onna (後方女: Backwards Woman). Her old name was Gureimisu, Ushiromuki and Lily. Hannah has a different AI than other monsters. Monsters in Chapter I and II have TeddyAI, and monsters in Chapter III and IV use the chase AI made by Ph4ntomx. Except, Hannah has a specific AI modified by Virtumation so that Hannah can walk through the bushes and also see you inside of bushes. Hannah's oldest version had flashing images as a Jumpscare. For some reason, Hannah's earliest and alpha model share the same jumpscare. Hannah's previous model and beta model also share the same jumpscare. Hannah's oldest model is featured in Chapter 4's current badge. For some reason even if your in a safe zone. She will get stuck on top of it. Hannah's model was walking backwards in the early version. Probably a reason why she has "Backwards" on one of her outdated alias. For some odd reason, Hannah's Jumpscare doesn't pop up. Hannah is one of the slowest monster in Tree Yard, however she can outran Valerie in the early version. in the leaking of Tree Yard's Upcoming yet cancelled revamp, Valerie has to stole her lily to open the house with the key.

Reference(s): https://tree-yard-remaked.fandom.com/wiki/Hannah