Densha Otoko 電車男
Based on the purportedly true story of a 23-year-old otaku who intervened when a drunk man started to harass several women on a train.
The event was chronicled on the Japanese mega-BBS 2channel. This led to the compilation of the relevant threads in the book ” 電車男, The story of the Train Man who fells in love with the girl, Hermes” by Hitori Nakano.