Grandma: from NieR:Gestalt 

The character Kainé, from NieR:Gestalt -- where the original version of the song comes from -- has this back story:
Though she is secretly glad to have Nier's company, she has already learned to survive on her own due to her grandmother who she loved dearly, her skill with twin swords, and her ability to wield magic.
The only person that showed her kindness and protected her was her grandmother Kali, with whom Kainé lived her childhood and inherited her attitude from. She held both love and respect for her grandmother who accepted her ...