Straight up: The rarest sencha flavor to find is grassy sencha.
In fact, of every vendor I've ever sampled from, only o-cha has had any grassy flavored sencha.
Indeed, grassy sencha is among my top desire in a sencha.
For example, o-cha has miyabi, Sae Midori, Kirameki and perhaps others that have that wonderful grassy flavor.
But if you try to find a grassy sencha from any other vendor you're SOL.
I felt compelled to bring this up because considering how much I love grassy flavored sencha--you'd think other retailers would also offer some.
Were you able to participate in the OTTI last year that was asamushi versus fukamushi? One of the offerings there (from togei) was very grassy. That might be another potential source for you to check out...?
FYI, that sencha in the tasting from togei was very reminscent of the Korean green teas I tried a year or so ago from Hankook. After the sencha tasting, I went back to the last of the Jeong Seon from Hankook and enjoyed it more than I did at the first go-round when I wrote the review. I called it briny there, but there was also a strong grassy vegetal flavor, and it was quite distinct from most sencha.