Kreitz studied Visual Design at the precursor of the Hamburg University of Applied Sciences and spent one semester at the Parsons School in New York.

[3] Kreitz drew Sorge's covert activities in Japan between 1933 and 1944 in black-and-white, expressionist images, hiding the future political events.

[6] The first event was the return from exile of German writer Thomas Mann in 1949, and the last dealt with the financial crisis following the crash of Lehman Brothers Bank in 2008.

[7] Other works by Kreitz have been graphic novels based on books for young adults by German authors Erich Kästner[8] and Uwe Timm.

[9][10] In the 2020 book about German-East Asian Encounters and Entanglements: Affinity in Culture and Politics, Kreitz has been called "one of the most celebrated German artists working in comics and graphic novels.