A period(pun absolutely intended) of puberty where a male teen would feel horny as shit and masturbate several times a day. It will only become Dark Days if the addiction left the body before
adulthood. So adult
perverts by definition never had a Dark Day because they
never left it.
My Dark Days started because some anime comic artist just decided to make their creations too "cute" which absolutely burns my
13 year old brain like
diesel and turned me into a pervert. Luckily I have left my Dark Days by considering just how degenerative that is and I have started a
new life where peace and happiness last longer than a masturbation session.