Matthias T. J. Grimme

June 1953, in Hamburg, Germany), stage name Tatsu Otoko (竜男Dragon Man), is a German author, publisher of sadomasochistic literature and magazines, a photographer and a rope artist in Japanese style bondage.

He met Japanese bondage riggers, including Eikichi Osada, Akechi Denki, Chiba Sensei, Randa Mai, Yukimura Haruki, Osada Steve, Kinoko Hajime, Kazami Ranki, Mira Kurumi and Yusuji Watanabe.

Grimme was co-organizer of the first public SM parties in Germany, "Les Fleurs du Mal" (until 1998).

He works as a BDSM performer and as an SM and bondage teacher, running his own workshops in Germany and abroad.

During BoundCon 2017, Grimme received a Lifetime Achievement Award for special merits in the bondage scene and for his lifework.