As usual, ice cream is the answer to our problems.

So here’s kind of an odd aspect to traveling in Japan. The Shinkansen bullet trains, as you’d guess from their name, are incredibly fast, able to run at speeds above 300 kilometers (186 miles) per hour. And yet, you’re likely to find yourself with time to kill while riding them.

Because they’re so fast, Shinkansen trains are used for long-haul traveling. Now, if you’re a mature adult, quietly sipping your special Shinkansen beer as you gaze out contemplatively at the views of Japan streaming past the window, that down-time is a nice moment to pause and reflect between the destinations on your Japanese journey. But for young kids, after the initial excitement of “We’re on a train that goes really, really fast” wears off, time on the Shinkansen can be boring.

But since Japan always values good manners, you won’t want your antsy kids to get rowdy or noisy and disturb the other passengers. So how can you keep them quiet and occupied? Simple, says Japanese dad and Twitter user @1042limit: just buy them some of this special ice cream they sell onboard the bullet train.

Granted, we’re always happy to accept ice cream as a possible solution to a problem (as well as our personal lord and savior), but how much good-behavior time is this really going to buy you? Kids can inhale desserts in seconds, and once they’re done, they’ll be back to being bored plus have all the extra energy provided by the sugar of their sweet treat, right?

But that’s why it’s important to buy them the ice cream onboard the train, and specifically to buy the Japanese brand called Sujahta, which is a mainstay of the food carts attendants push up and down the aisles of the Shinkansen. Fans say Sujahta’s rich, creamy flavor is similar to that of Häagen-Dazs, but it’s not the taste that makes Sujahta a life-saver for parents, but its hardness.

▼ “As usual, Sujahta ice cream is seriously hard.”

Sujahta has an extremely small amount of air within its cream, making it extra-dense. But of course kids can’t resist desserts that are right in front of them, right? So when you hand you kid a cup of Sujahta, you’re not just giving them a snack, but an attention-consuming activity as well. After @1042limit gave his two-year-old son the treat, he says he spent the next 30 minutes quietly and contentedly scraping away at it, without fussing to get up out of his seat or otherwise vocally complaining even once. “It’s like a treasure from the gods,” @1042limit reverently said.

▼ Sujhata is so hard that if you, as an adult, are in a hurry to eat it, some experienced Shinkansen passengers recommend also buying a hot coffee and placing the beverage’s cup on top of the ice cream to soften its top layer.

Other Twitter users chimed in with their own tales of the brand.

“I started eating some Sujhata when my Shinkansen left Odawara Station, and it took me until we were in Nagoya [about one hour and 10 minutes away] to finish it.”
“I used to be a food vendor on the Shinkansen, and sometimes we’d get complaints from customers saying ‘This ice cream is too hard!’”
“I always buy a cup at the same time as I buy a bento boxed lunch, thinking that by the time I’m ready for dessert it’ll be really soft…but it never is.”
“I recommend pouring a little whisky in to soften it up. Tastes great too.”

▼ Or you can use hot coffee to make a Sujahta affogato.

While Sujahta isn’t exclusively sold on the Shinkansen, it’s heavily associated with the high-speed trains, and waiting until you’re onboard to purchase a kid for your kids (or yourself) ensures it’ll be firm enough to keep you from feeling like there’s nothing to do. At about 290 yen (US$2.60), it’s not the absolute cheapest ice cream around, but it’s still a bargain for delicious way to keep your trip in Japan happy and stress-free.

Source: Twitter/@1042limit via IT Media, Yajiridori