after reading the comments and seeing that there is no winning suggestion, nightspire and umbra suit is the most likely... with the term night and umbra meaning shadow... a thought came to mind, nocturne of league of legends... and as everyone knows... our MC is a LoL player during chapter 1... and coincidentally, I am a diamond rank nocturne player... since you like the concept of night... we going nocturne :P
to make it more dramatic and potentially upgradable like Tony's iron man, like him naming it Iron man: mark 1, Iron man: mark 5 [Suitcase Armor], or Iron Man: Mark 33 [Silver centurion]
Then this is called Nocturne: Mark 1 [Umbra Sentinel]
basically hero name with the suit is Nocturne... model 1: Umbra Sentinel
Umbra is shadow, sentinel is watcher.
His an assassin in the shadows... fitting name for the suit.
any complaints?