The two primary types of raw fish slicers used in Japan are yanagiba or the takobiki. It’s basically one of those Kansai vs Kanto things except that you tend to see yanagi way more often.
But sushi got more prestige as a job (trust me, for Japanese people 30 years ago, while your neighborhood sushi chef was a cool dude, you didn’t necessarily think of him as an esoteric master of culinary arts). Since the job got cooler, people started caring more about appearances and there was this sudden mystique that exploded around sushi knives (which I think in turn led to the j-knife world we live in now).
Basically, sushi chefs started spending more on knives. First fancier handles, shinier steel, etc. After a while every fancy sushi chef had a mirror polished honyaki shaku-sized stand-in for their masculine and culinary insecurities. So how does one stand out even more? Different shapes.
The kirituke shaped yanagiba and the sakimaru takobiki are both fairly new and are stylistic choices. The kiritsuke has been around as a shape for a while but not as a hybrid with a yanagiba (it doesn’t make much sense to call a shape a willow leaf if it’s not shaped like a willow leaf anymore). But man does it look COOL.
Same thing with the mini samurai sword. I mean sakimaru takobiki.
As a chef who was trained to use the full length of my knife both in slicing and portioning, as well as to use the natural curvature of the blade to aid in more ergonomic slicing, I find the new variations more about appearance’s sake than about any practical use. But then again I’m old-fashioned and haven’t actually given either shape a real shot. Maybe a younger sushi chef on here would have a more generous interpretation?