Out of curiosity I bought one box of these today. I remembered wrong, it's "Cherry oranges - mini mandarins of China" what it says on the label. What else it says in small print is this: "Product variety: Citrus kinokuni ex Tanaka." So there's the answer to my question (and Gaia-project was right), I just didn't notice it on first time. It also says there that the name Cherry Oranges is a trademark of Uniagro and that made me find this site:
http://www.uniagro.ch/en/products.html?page=shop.product_details&flypage=flypage.tpl&product_id=107&category_id=27
Quite nice flavor, very sweet, but the price (over 10 euros per kilo) is much too high. Unfortunately the ones I have eaten so far have been totally seedless, would have been fun to try growing these.
(Edit: I don't understand why it says "ex Tanaka" since to me it looks like Tanaka is the guy who named the species, not a cultivar name)