User blog comment:Hitsuji Mamoru/Servant Creation Room 2 : Guess of the Who/@comment-27971189-20170613081035/@comment-30937535-20170720210455

With what you have given us, I'm thinking of some kind of siren like Lorelei or Melusine, but I' unable to make a head of that fusion thing. Well, Melusine was forced to chance her form regulary(differing on the source). It could be that you split her identities/forms up for the summoning.