It seems like Japan is having hospital diversion issues similar to the US--and the rest of the world. From the article:
The deterioration of emergency medical services has become a nationwide worry. In October, a pregnant woman transported by ambulance was refused admission to eight hospitals in Tokyo and died after giving birth. In December, an elderly woman seriously injured in a traffic accident died after she was refused admission to six hospitals in Fukushima and Ibaraki prefectures.
The Fire and Disaster Management Agency's 2008 white paper says that, in 2007, an ambulance took an average of seven minutes to pick up a patient — 0.4 minute more than in 2006 — and 26.4 minutes to take the patient to a medical institution that accepted him or her — one minute more than in 2006. Both times were the worst ever. The 26.4 minutes to transport a patient was 6.5 minutes longer than 10 years ago.