Degenbrecher

Degenbrecher, better known as the Black Knight (not to be confused with Blacknight), is a boss enemy in Arknights. She is one of the deuteragonists of Break the Ice, where she also acts as the main boss; before BI is released, Degenbrecher is mentioned in the Maria Nearl event and Letter, part of Preluding Lights. source: arknights fandom wiki