Konichi wa
Some of these get referred to as "cocktail tomatoes" or "boutique tomatoes" but they are similar in flavor qualities. Some just lack the elongated appearance.

There are two I can think of from a Japanese based company- Sakata.

• Sweet Elite F1

• Sweet Hearts F1

• Sweet Quartz F1

I would also suggest

• Smarty F1

there are a number of ones released to the commercial market without names

BHN-624
Felicity (hazera seed)
Jolly Elf (boasts a avg brix rating of 10)

I took some advice I read on this forum and saved seeds for Santa F2. It worked well last year and I'll try it again this year.
My family and I also like Sugary quite a bit. I would say it is sweeter and not as "tomatoey" as some.
I'm trying Sprite again in a container. Last year my Sprite seedlings succumbed to damping off but that was my fault.

I don't know if you can get them in Japan, but I have tried about 10-12 grapes, and my favorites are Sugary, Tami-G and Golden Honey Bunch. (And of course Green Grape, but despite its name, it's round, not grape-shaped)

Carla in Sac