The series has ended, yes. There are 17 volumes (18 if you count the "Children" volume of character backstories that I believe was only released in Japan) containing a total of 99 chapters. As far as I can tell the atuhors haven't written any other manga.
(edited by ACDragonMaster)
A Fandom user·
i finished it already and yes its all 99 chapters. but it was great story! this is one of my favorites.