"Three-quarters of those who committed suicide were male..."
Like all other violence, most suiciders are male. I venture this is in-line with stats from other nations.
Actually, the suicide rate in Japan is very high relative to other nations
What is in line with other nations is the violent death rate - the sum of deaths due to murder and suicide.
Interestingly, nations with very low murder rates (Japan, Switzerland) have high suicide rates, while nations with high murder rates (Mexico) have very low suicide rates.
The US is around average of all nations in both categories.