Yochanan was born on January 1,1925 in Vienna Austria, to Ya’acov Yoseph and Miryam Frieda. His father was a Rabbi, active in Hamizrachi Movement who assisted Jewish pioneers from Eastern Europe to reach the Land of Israel. Yochanan was aware of his father’s activities and absorbed his home’s Zionist Jewish atmosphere. He studied in Austria’s only Hebrew High-School. With the rise of the Nazis, his family moved to London. Yochanan continued studies in the Yeshiva, and studied for external examinations at London University. His ambition was to make Aliya but he was too young and attached to his parents. Later, his father died relatively young; Yochanan had to remain and assist his mother. He began working in the diamond industry.
He was shocked by the news in 1944 regarding the fate of European Jewry and closure of the gates of the Land of Israel by the British authorities, to Jews fleeing Europe, while all other countries were refusing them entry. He looked for a way into the Hebrew underground – to Lehi. He found the connection, joined the local branch and dedicated himself to the underground’s work. He underwent an ideology course, and trained in using weapons and explosives. Yochanan gathered information about potential targets in London, photographed and forged identity papers and other documents, did surveillance on potential targets like Roy Faran, killer of Alexander Robovitsch in Jerusalem ( later a letter bomb was indeed sent). A weapons cache was installed under the floor of his room but when police showed up and searched, they found nothing. Yochanan made Aliya June 22,1949 settling in Jerusalem. He worked as a clerk in the Ministry of Commerce and Industry. Between 1951-1953 he served in the Israeli Defence Forces, in the Infantry. After discharge, he returned to his previous line of work. He married Ruchama Tova Bernstein (daughter of the editor of Hatsofeh) July 1,1954, and they had four children. Yochanan became Deputy Director of the Food Import Department. He received the ALEH medal and the Lehi medal.
The couple have twenty grandchildren and a great-grandson, mostly inhabitants of Judea and Samaria.