Asayo Sakai banged on the front door, demanding to be let out. She was at her daughter's apartment, where Asayo has lived for the past six years. She has no memory of how she got there or what she's doing there.

As her daughter, Akiko, blocked the way, Asayo, 87 and suffering from dementia, lashed out, hitting and biting. The scene repeated itself with agonizing predictability for a solid year until one day Akiko, exhausted, gave in and opened the door, letting Asayo wander the streets of Osaka.

"I thought, 'Get out of here, if that's what you want,' " Akiko said. "Mom turned into a monster and I couldn't handle her. I thought my life was over."