A 1-year-old boy fell to his death Sunday from the ninth floor of an 11-story apartment building, police said.A passerby found Masashi Sato at around 8:15 a.m. lying bleeding on the ground outside the building in Yodogawa Ward, Osaka, police said. He was pronounced dead at a hospital.His family lives on the ninth floor, about 23 meters above the ground. Police believe the boy fell accidentally from a window.Investigators quoted Misa Sato, 35, the mother of the boy, as saying she had occasionally placed a set of small steps under the window so he could look outside.She went to bed Saturday night with the window open about 10 cm because the air conditioner was out of order, the police said.