Yomiji is an enigmatic entity who holds sway over gates between worlds. The flavor of the card's mechanic is that it uses that power to seal off the after-world from legends, hence keeping them from dying.
But Yomiji was actually depicted on another spell previously. Take a look at this piece of art from Champions (below):
Hideaki Takamura had a new interpretation of the spirit when he illustrated Yomiji, but it's definitely the same creature from Blessed Breath -- note the tentacles and the details of its robe. Although Yomiji's concept and identity wasn't defined as fully during Champions as it was for the design of Betrayers, we can see in retrospect that the kami was providing protection to his fellow creatures early on.