All you need to know about this abomination is that it says you should "Shake Before Drinking."
Why, God? Why would you visit such punishment upon mankind? Umeshu itself is a mixed blessing - a plum wine/liqueur that's very delicious and very sweet, like a more natural version of a wine spritzer. It's enjoyable like Diablo II - after a couple of fun hours you're going to feel really bad about yourself.
So anyway, Jelly. It's one of the weirder trends in Japanese drinks, alcoholic and otherwise. People who don't read Japanese are at some point certain to end up with something that looks like grape juice, sports drink, or even cola, and find their first sip full of what feels like curdled milk.
In short, as with most of mankind's sufferings, this is one we have visited upon ourselves. Drinking this is a reminder that I could live in Japan for a decade and there are still things I would never understand. It's also very tempting to see it as a sign that the Japanese are, as a nation and a people, of the devil.