Namazu takes place in the Usagi Yojimbo/TMNT crossover one-shot “Namazu” , not in a main IDW TMNT multi-issue storyline. It’s a stand-alone 2017 crossover story where the Turtles team up with Usagi to restore the capstone holding the giant catfish Namazu in place.

Where it fits

  • It’s a special crossover issue , written and drawn by Stan Sakai.
  • The story is also referred to as “Namazu or the Big Fish Story”.
  • It connects to Usagi’s world and Japanese folklore more than to a specific long TMNT IDW arc.

In plain terms

If you’re asking which IDW storyline arc it belongs to, the clean answer is: none of the main arcs. It’s a standalone crossover one-shot that sits alongside IDW TMNT continuity rather than inside a numbered Turtle storyline.

TL;DR

Namazu is the 2017 TMNT/Usagi Yojimbo one-shot crossover, not part of a main IDW TMNT storyline arc.