The Angel of Diligence.

She works hard and never complains.

She would sacrifice herself if that solves a problem. However, she's a little forgetful, and her inventions are all often flawed in some ways.

Despite that, she never stops researching and developing them everyday, and that's proof to her proactive attitude.

She's ambitious, and she doesn't quit. Despite being an angel, she's quite close with Demon Lords like Belphegor and Astaroth. They even discuss about inventions occasionally.