The Heroes in a Half Shell and the Rabbit Ronin join forces once again in this new adventure from beloved Usagi Yojimbo creator Stan Sakai! The Teenage Mutant Ninja Turtles pursue the evil cyborg genius Dr. WhereWhen through a time portal… and emerge in feudal Japan! There, they encounter Usagi, 20 years into the samurai's future but decades after the arrival of Dr. WhereWhen… who has already carved himself a fiefdom using mechanized clockwork samurai robots… with the intention of conquering both the past and current timelines! Kevin Eastman and Peter Laird's TMNT first crossed over with Stan Sakai's Usagi Yojimbo in 1986, and since then, their encounters have extended to numerous comic adventures and multiple animated series. This newest tale deepens the connection between the anthropomorphic animals as they struggle to save both their worlds from a sinister villain the likes of which none of the heroes have seen before!