So is this a flashback, or a timeskip?
Did the crazy lady with the chains in the previous chapter knife him to force him to reincarnate, and that's what we're seeing now (timeskip)?
Or is this him recalling when he reincarnated as Nargoa and remembered the crazy lady as a kid -- i.e., this is before he entered the tower.
And is she gonna turn out to be a Yandere stalker or something?