Six of Crows is essentially a tale of a bunch of shitty teenagers who try to pull off the biggest heist of all time and it fails/succeeds miserably. Inej is an acrobatic spy/assassin who is about sixteen and is quiet, shy, and definitely not a singer, BUT she is very kind and loving despite being surrounded by terrible people and also making poor life choices.

So, honestly, a monster barreling through Ketterdam (the base of operations for their gang) would make it look nicer, in Inej's professional opinion. And she is not singing. :|||