Tojiko herself isn't present in the picture. Without context, it's just Futo looking at an earthenware jar that's covered in ofuda. So, no. Her tag doesn't apply.
But this jar is Tojiko herself. If you know the lore you know the context. Especially that title of this artwork is "goodbye".
That's the thing.
Danbooru's tagging criteria is "Tag what you see, not what you know." The tags reflect what is seen in the image, not typically what is implied without some very convincing evidence that can be surmised with just a quick glance. Also can be understood entirely out of context.
If the jar had Tojiko's radish legs sticking out, that'd be a different story. There's a reason we don't tag Mystia Lorelei just because we see her grilled eel shop without even a sliver of her silhouette in frame.
