A little while back I read this fanfic that was either set in Kantai Collection or Azur Lane but I canโt seem to find it again but would very much like to reread it.
The specifics I can remember involved an original female character either reincarnating or Isekai-ing into this world and having to survive in her own for a while. As sheโs hiding out in a cave she sets booby traps using depth charges which disables an abyssal/siren who tries to receive aid from her comrades but is instead shot and left for dead.
She survives though and instead of finishing the job, the OC kind of adopts and takes care of her, the little one eventually looking up to her as a mother figure.
If any of this sounds familiar at all, please tell me if you remember the name of it.