We have been successfully organizing two-day self-defense seminars for students at Berlin’s universities for more than fifteen years on a regular basis. These courses require absolutely no previous self-defense or martial-arts knowledge:

Women’s self-defense for female students
14/15 September 2019, FU Berlin (Susan Bergner and David Krüger)

For people who regularly train Ninjutsu there are plenty of more Ninjutsu-seminars in and outside of Berlin. Berlin seminars can be found on the Berlin Bujinkan-Portal. German-wide Seminars can be taken from the Erlangen Seminar-Portal.