I don't think this pic related to Nezuko
since the source didn't tag about KMY and in her mouth is just a ninja scroll not the Nezuko's bamboo tube.
(Just accidentally have same VA.)
.
Should remove unrelated tags...

Yeah, this is about her song from the 4th album; in the game storyline, it's for a student film project about a ninja girl, so she spends a couple of bond episodes playing ninja.

(There may have been cross-series synergy prompting that choice, of course.)