Koei Tecmo filed a new trademark for Yaiba: Ninja Gaiden Z in the United States on January 2.
Yaiba: Ninja Gaiden Z is a zombie-themed spin-off of the Ninja Gaiden concepted by Comcept and developed by Spark Unlimited. It was released for PlayStation 3, Xbox 360, and PC in March 2014.
Going through the database of Koei Tecmo’s past trademarks in western territories, the company does not seem to file trademarks for anything that it does not plan to use at that point and time. The only exception seems to be a trademark for Eat! Fat! Fight! filed in December 2016 in the United States and January 2017 in Europe, which was never used. Eat! Fat! Fight! is a WiiWare title that released in 2009.