Judge Shizuka Asakura said Mori hid the body in a closet and later moved it to a freezer after it decomposed, adding that the daughter had behavioural problems and had committed acts of domestic violence.

Are we supposed to get from this that it was an act of self defense when she was killed?

https://www.independent.co.uk/asia/japan/japan-mother-hiding-body-freezer-jail-b2887538.html

More details are here, if you're curious.