Chapter 19:
Koto takes her mother from the Shrine's Holy Grounds to the Looking Glass City.
Chapter 20:
The three siblings enjoy their time with their mother, but...
Chapter 21:
Koto tries to find out the secret of her birth from her mother, but instead she's asked to save her poor father.  With no place for her feelings to go, she takes them out on Myoue.
I'm sorry for making you 
go through all this.
Es tut mir leid, dass du all 
das durchmachen musstest.
Perdona por hacerte pasar por esto.
Siento haberte hecho pasar por esto.
Je suis désolée
pour toute cette agitation.
Desculpe fazer você passar por tudo isso.