He is the protégé of Hideaki Anno, and a longtime animator at Gainax. Tsurumaki's first project at Gainax was as an animation director for the 1990 TV series Fushigi no Umi no Nadia; Tsurumaki was also director of the humorous "omake" (extra) sequences that went along with the TV series, and producer of "Nadia Cinema Edition". In 1995, Tsurumaki served as an assistant director under Hideaki Anno in Gainax's landmark series Neon Genesis Evangelion, in which role he handled production, art director and setting assistant for some episodes. In 1997, he directed episode 25, the first half of the cinematic conclusion to the Evangelion series, The End of Evangelion. He assumed directorial duties for the 1998 TV series His and Her Circumstances after Anno abruptly left the project. In 2000, Tsurumaki officially made his debut as a full-fledged director with the six-part OVA series, FLCL. In 2004 he directed the hit sequel to Gunbuster called Aim for the Top 2! or Diebuster. He is currently working as a director on the new four-part feature Evangelion film series, Rebuild of Evangelion.