The matter of the Mitsunobu Toyo's death is really mysterious...
He was killed by partisans (exactly, by the "XI Zona Patrioti" unit that was in command of Manrico "Pippo" Ducceschi).
He was in Italy for a diplomatic mission on behalf of the Japanese government. However, I enclose a very interesting link:http://xoomer.virgilio.it/laurapog/PIPPO/toyo_e.htm
"Et fia 'l combatter corto / che l'antiquo valor / nell'italici cor / non è ancor morto"