Many Chinese make the trip for a chance to reminisce about the "good old days" of iron-fisted central planning. (The Washington Post)

The Chinese tourists were hesitant for a second, perhaps startled by their North Korean guide’s perfect use of Chinese curse words, perhaps surprised by the sentiment.

“F--- the Japanese devils! F--- their mothers!” Mr. Lee, the guide, shouted out to a busload of visitors making a day trip across the Yalu River into Sinuiju, North Korea.

Recovering from their initial surprise, most of the middle-aged Chinese visitors joined in. “F--- the Japanese devils! F--- their mothers!” they cheered back, with whistles and clapping, in an expletive-filled echo.

It was a bonding moment between the neighbors.

The excursion into North Korea, from this border town in northeastern China, took a group of 51 Chinese tourists, by turns curious and nostalgic, into the land of the Kims. Their small green bus, which carried them over the river and back in time, was for Chinese visitors only. The people on the bus did not want to be fully identified, because it could go badly for them, but here is their account:

Socialist realist billboards at the Sinuiju Women’s Park. The park was built completely by women, said Mr. Lee, a North Korean tour guide. (The Washington Post)

“It’s like going back to elementary school,” said Lin, a professor from Fujian. And that was not criticism.

First stop: a central square in Sinuiju, with its new bronze statues of Kim Il Sung and Kim Jong Il, the first two generations of the world’s only communist dynasty. The tourists were told to get gaudy bunches of flowers — at $3 a pop, that was $150 for North Korea — to place at the feet of the two Kims.

They had not even left the square before the flower vendors began clearing away the flowers and placing them back in their plastic baskets for the next wave of tourists. “They should at least wait until we leave,” said Gu, a middle-aged businesswoman from Shenzhen. “They need to work on their skills.”

Relations between Beijing and Pyongyang have become strained in recent years, as North Korean leader Kim Jong Un has repeatedly defied and snubbed Xi Jinping, the Chinese president, who is three decades his senior and many multiples his power.

But even as economic and political ties wobble, tourism has become an important source of foreign revenue for North Korea, and it is more easily extracted from Chinese tourists, who tend to be obedient and sympathetic, than, say, Americans, who have proved less so.

Many Chinese come for what might be described as “communostalgia” — a chance to reminisce about the good old days of iron-fisted central planning.

With Sinuiju not having a lot of what would be called, in any other country, tourist attractions, the next stop was a museum at which the guide talked, crying, about the time Kim Il Sung visited. The unfazed Chinese tourists quietly waited for it to end.

Luckily, they soon found themselves in the museum gift shop, where cases displayed creams and lotions made in the local cosmetics factory — another of Sinuiju’s attractions.

“This stuff is so cheap! And it’s natural and pure. North Korea isn’t polluted like China,” Gu said. She bought a dozen gift sets. That was $550 more for North Korea.

Back on the bus, Mr. Lee, a slickly dressed 27-year-old, started his anti-Japanese tirade, simultaneously shocking and uniting his audience. But he did allow that not all Japanese people are bad.

Then Mr. Lee led the group into a restaurant designed for tourists. After a lunch of fried fish, kimchi, glass noodles and pork with potato, North Korean women in bright traditional dress began singing old Red Army songs, transporting the older Chinese tourists back to their youths. Gu and her friends had tears in their eyes. “These are songs we sang when we were growing up,” one said.

Pretty young North Korean women took middle-aged Chinese men with beer bellies by the hand and dragged them onstage to sing together, while the guides snapped photos.

The North Korean tour guides were perhaps better proponents of Chinese nationalism than the officials Xi has dispatched to try to whip up domestic fervor.

After another gift shop, the final stop on the tour was a kindergarten, where 5-year-olds welcomed the tourists in Korean and Chinese. The most popular performance featured five boys dressed as North Korean soldiers going through field exercises. Then out came two dressed as Japanese soldiers, with rats’ tails, and then one as a senior American officer, with a wolf’s tail. The Chinese tourists lapped it up.

“Young kids in China these days are too spoiled, too materialistic,” said Qi, a man from Liaoning province. “We should have more nationalist education in our schools. Look at North Korea. They know how to educate kids!”

At the end of the performance, one of the guides announced that the teachers would happily accept any gifts for the children. Some tourists offered pencils, cookies and sausages they had brought from China.

On the bus, others felt bad they had nothing to give. Not to worry. Mr. Lee had a plan.

The children had trained for a whole year for this performance, he said. “They have eaten bitterness,” he said, using a Chinese phrase for enduring hardship.

Passengers began handing over Chinese notes worth $7.50 or $15.

When they arrived at the tourist center on the border, it was time to hand over something else. This time, it was their cameras, which had to be checked for photos deemed undesirable.

As the North Koreans were censoring the photos, the guides came out with flashy individualized folders featuring pictures of each tourist at the sites they had visited. There were photos of them singing with North Korean women at lunch, pictures from the museum and snapshots of a “chance” encounter in a park with a couple on their wedding day.

The tourists were surprised at all of the trouble the North Koreans had gone to, and so quickly. Many did not have photos of themselves. And it was good to help the poor, starving North Koreans, wasn’t it? More than half of the tourists handed over $30 for their folder — exorbitant at local prices.

“They’re very smart,” Lin said. “While our photos were being deleted, they were selling us pictures. From the first step we took in this land, they had planned out exactly how to get our money.”

Congcong Zhang in Sinuiju, North Korea, contributed to this report.