Years ago I went on a culture exchange program to Japan, and there went to a tea house. The green tea was frothy and for a sweet, they gave me this sort of jelly that was in the shape and color of an ice cube, not translucent, and had some kind of raisin thing in the middle.
I want to relive this moment – so can anyone guess as to what that was?
I have some Hello Kitty thingies of those at home right now. Alas, the big container where the individual units came is gone and I only have the individual containers (shaped and sized like a thimble) and they only have some minimum of japanese writing (which I cannot read) and that I presume is just the flavor.
The only thing I remember is that the thing in the middle (shaped like a cube in mine) was some form of seaweed product. The gelatin itself comes in all different colors, some of them clear, some translucid and even opaque. All impossibly sweet to my non-toddler palate.
I can’t remember for sure – perhaps it is like the Hello Kitty thing. Or perhaps it is Yokan, white kidney bean paste version?
The hello kitty might be the “hi chew”
http://www.asianfoodgrocer.com/product/hello-kitty-hi-chew
but at the tea house, i doubt they were serving anything not freshly made
No, not that. This was more like gelatin with a little cube of spongy seaweed in the middle.
It is likely that it is the totally bastardized industrial version for children of something better.
It was almost certainly some type of yōkan. It may also have been uirō, which is somewhat similar. However, it’s probably going to be difficult to reproduce the moment exactly: there is a tremendous variety of Japanese sweets. There are a lot of local variations and most confectionary makers have their own creations.
And, for the record, Japanese sweets don’t use gelatin. Agar is always used and it doesn’t have quite the same consistency as animal gelatin.
The mother of a Japanese friend of mine sent her some jelly-like confections that were clear and had some sort of flowers in the middle. Very oshi and also pretty.
It might also have been a konnyaku jelly. (Yet another Japanese food product that can kill you.) It really is almost impossible to guess exactly what you had because, as jovan said, there are so many variations.
The tea was definitely matcha. It’s traditional to serve something very sweet with the tea, not as a way to ameliorate the bitterness, but to contrast with and actually enhance the bitterness. I’ve most often had some kind of higashi, which is like a very sugary powdery cookie, or yôkan served with matcha.
Konnyaku is a lot less likely, though, as it’s almost always used in savoury dishes. I’ve seen a few mentions of traditional konnyaku-based sweets, but I’ve personally never eaten or even seen any.
They’re really common in my area. Or at least they used to be until they had the warnings about choking 
Then again, they produce a lot of konnyaku here, so I guess it’s no surprise that it would be more widespread here than in the Kansai area where you are, if I’m remembering right.
The wiki entry for Konjac (konnyaku) mentions knojac candy which sounds exactly like what I have at home (which is not to say that it is what the OP had, of course)
Actually, technically I’m in Tōkai, but I can see Kansai from my house.
There’s another possibility for gelatinous sweets are kudzu-based confectionaries like kuzu-manjū, better known here as mizu-manjū.
I’d like to stress that to compare Hello Kitty candy with the kind of stuff served in tea houses is like comparing gummy bears with Henri Leroux’s creations.
Yes, I was going to say that you probably had a konnyaku jelly. The cube in the middle was probably coconut, it’s the jelly that’s seaweed-based. Mmm, I love me some lychee-flavored konnyaku jelly! Although the authorities had to go and be a buzzkill by removing the coconut chunk and replacing it with coconut bits. Just not the same.
