You'll find plum wine and Yukari powder (which tastes like salty, sweet, fruity black tea leaves and looks a little like black tea) at any specialist Japanese...
I can't imagine how that would've tasted. The rice seasoning suggested is made from red shiso leaves and while it is salty, it doesn't contain fish flavours or anything like that. I hope you try again with the correct ingredient, it adds a lot and I'm sure you'll enjoy it more.
So I tried this. When I googled "Yukari rice seasoning", every result pointed me to "Furikake". Yukari is the brand. My furikake seems based on shredded sushi nori and other "fishy/salty/umami" flavored bits which I put in the coffee grinder to make a powder. Then I made the cocktail per the instructions.
My only recommendation is to not let the lemon juice or the grenadine get control of the flavor. Don't be afraid to dump more of the rice seasoning in than you are comfortable with.