Although the recipe called for only two eggs, I used four because the ones I had were so small. I bought them at my local produce stand, and they were labeled eggs from "meat birds" (nikku tori). I'm not sure what that means - after I got home with them I had a moment of panic when I thought it might indicate that they were fertile eggs with embryos inside. Luckily, that doesn't appear to have been the case. Maybe chickens bred for meat just lay small eggs, which then sell at bargain prices from produce stands, who knows? At any rate, like all Japanese eggs, they had beautifully orange (though undersized) yolks, and they seem to be fine for making cake. That's melted butter in the Pyrex pitcher on the left - French, salted butter. It's such fun having access to ingredients from all over the world.
The small, overripe plums that star in this cake are another item I'd never seen in any U.S. supermarket, and I'm not sure what their proper name is in English. They're called "prunes" in Japanese, but whether they're actually the variety of plum that gets dried to make prunes, I don't know. They're only a little bigger than a large grape, their pits are the size of a flat almond, and they're much sweeter than the slightly astringent ordinary plum. For the cake, I split them all in half, laid them cut-side down in my buttered 8-inch square baking pan (a change from the recipe, which calls for an 8-inch round cake pan), and poured the batter on top. The cake is meant to be inverted in the style of tarte tatin or any other upside-down cake. I didn't have the nerve to try it, and since it's just me here, there was no need to impress anyone with a stunning (or more likely, patched-back-together) presentation. Turning it over one piece at a time, as I eat it, is good enough for me.