Johanna Tumbuan Masdani (29 November 1910 - 13 May 2006), also known as Jo Masdani, was a pioneering figure in Indonesian independence. She was born Johanna Tumbuan in Amurang, in the region of Minahasa in North Sulawesi. She was present during two important events in Indonesian history, namely the Youth Pledge during the Second Youth Congress (or "Kongres Pemuda Kedua") in 1928 and the Proclamation of Indonesian Independence in 1945. She graduated and taught in the Faculty of Psychology at the University of Indonesia.