It's nail polish names like these that really make me nostalgic for the good ol' days. You know, the ones where women were in the kitchen, African-Americans were at the back of the bus, and Asians were in internment camps.
(suggested by Avii)
This name is pretty subtle, so let me break it down for you. You see, "miso" sounds like "me so," which is what all Asian people say instead of the grammatically correct "I'm so." Man, sometimes people who grow up speaking a different language don't have a perfect grasp of English. Ha ha, I sure love to laugh at them for trying!
Google backs up my intuition that the primary association with "me so" anything is the immortal "Me so horny" scene from "Full Metal Jacket." Get it? One of Japan's primary cultural exports, which OPI is taking care to celebrate in its Japan collection, is prostitution! Of course, the character in "Full Metal Jacket" was Vietnamese, not Japanese, but that's cool. They all look the same to me, too.
Also, I love how in classic OPI style, randomly inserting the name of a soup (a soup that is not even remotely the same color as this nail polish, I feel obliged to pedantically point out) makes this a brilliant pun. Wow, that's vichyssoise hilarious, you New England clam chowder morons.