Hiroshi Ōshima

Baron was a general in the Imperial Japanese Army, Japanese ambassador to Germany before and during World War II and (unwittingly) a major source of communications intelligence for the Allies. His role was perhaps best summed up by General George C. Marshall, who identified Ōshima as "our main basis of information regarding Hitler's intentions in Europe". After World War II, he was convicted of war crimes and sentenced to life imprisonment, but was paroled in 1955. Provided by Wikipedia