Chien is the blind girl of the Nine Sols prequel manga, (before the events of the game, the solarians are leaving Penglai).

When aged up, somehow she's was turned into a Dusk Guard by Eingong (nanomachines son), it looks like she's still blind and i guess they wanted to make her a boss fight, maybe Red Candle Games, can make a prequel game or DLC where you play as her before everything blows up.