I'm drinking Mets Cola, which is made by Kirin. I went shopping for Coke Zero this morning (they don't have Diet Pespi anywhere, only Pepsi Nex, which is lemony, which I don't like, so I've been drinking Coke Zero). Anyway, the drugstore had this stuff called Mets Cola, and it said zero calories, or thereabouts, so I bought a bottle.
I looked it up, and it appears that it came out last spring. It contains "an indigestible form of dextrin that can be used as a fibre supplement and restricts the body's ability to absorb fat when eating." Not to be outdone, Pepsi has come out with something similar here called Pepsi Special. I saw smaller bottles at the grocery store this morning, but didn't know what it was, so didn't get it. I wanted a 1.5 litre bottle or bigger, as well.
Mets Cola doesn't taste bad, so maybe I'll drink that the rest of my stay here instead of Coke Zero!
Image from Japan Today.