"I can't say thank you enough to them," the mother said of the officers. "I owe them the world, because they saved my world."
The children told police their adoptive mother starved, beat and pepper sprayed them when they failed to follow direction for videos, officials said.
The suspect had three knives and police believe he ambushed the woman when she walked into the building, NHK public television reported.
"Amazingly," no one was injured, police said.
The treatment is delivered through a one-time, 60-hour intravenous infusion that may improve symptoms within 24 hours.