He moved to Japan in 2023 when he was 26 to work in construction. During weekends he would often invite six fellow Vietnamese over to cook and chat to combat homesickness.

The first time they had only sung karaoke for 10 minutes before the police knocked on their door. The officers asked for their personal information, explained neighborhood rules and warned them to keep the noise down.

The police showed up again after someone laughed too loudly and disturbed a neighbor’s sleep. The third visit came when Minh was assembling a shelf and upset nearby residents with the noises.

Even when the group tried to stay quiet, just two people talking at normal volume could lead to another complaint. “I was shocked because we were already keeping our voices low but still got reported,” Minh says.

He later realized noise is a major concern in Japan. His next-door neighbors, an immigrant family with a baby, were also visited by the police when the infant cried at night.

For Thu Ha, 30, of Nam Dinh Province, the toughest adjustment in Japan was its strict trash-sorting rules.

When she moved into a rented apartment in Tokyo, she was given a booklet with dozens of pages explaining how to dispose of waste.

Trash is divided into inflammable, nonflammable, recyclable, and large items, with each having its own collection schedule. They must be placed at the collection point before 9 p.m. and keep it at home if she misses the schedule. Taking them to another area could result in a fine.

Several times she has carried a bag to the door only to bring it back because it was the wrong pickup day.

One evening, after work, she walked around with an empty plastic bottle, but had to bring it back home because she could not find a public bin.

Guidelines for sorting trash are plastered around neighborhoods and streets. In the case of plastic bottles, Ha has to remove the cap and label, throw them in the inflammable group and recycle only the bottle.

Milk cartons, soda cans and bottles must be rinsed clean to prevent odors. “I never imagined taking out the trash could be this complicated,” she says.

Minh and Ha are among many Vietnamese struggling to adapt to life in Japan. A study published in the U.S. National Library of Medicine’s PubMed Central found 45% of foreigners face adjustment issues due to Japan’s strict social rules.

Some 69% said they feel constant pressure to avoid inconveniencing locals. Asians have been found to adapt slower than western and Latin American immigrants.

Japanese culture values independence and discipline, while many Asian cultures emphasize collectivism. Behaviors like speaking loudly in public, dressing too casually or not sorting trash carefully are seen as disruptive in Japan, where order and rules are prioritized.

Posts about accidental rule violations on Facebook groups like “Vietnamese Moms in Japan” or “Vietnamese Community in Japan,” with hundreds of thousands of members, often draw thousands of comments.

TikTok videos showing how to sort trash or avoid noise complaints get millions of views, with viewers sharing lessons learned.

Nguyen Hong Son, chairman of the Vietnam Union Association in Japan, says following rules is key for newcomers to adapt and settle quickly.

Japan has some 620,000 Vietnamese residents, the second largest foreign community in the country. They live mainly in Tokyo, Aichi, Osaka, Fukuoka, and Saitama prefectures.

As the community grows, cultural faux pas have become more common. “Some behaviors normal in Vietnam are serious violations in Japan,” Son says.

For instance, many Vietnamese fly their national flags outside their homes to help others identify fellow countrymen, but the practice often irritates Japanese neighbors even though it is not illegal.

Journalist Murayama Yasufumi, who has visited Vietnam 60 times, says certain Vietnamese behaviors may surprise Japanese people, but it mostly stems from differences in customs and social norms.

Japanese are highly sensitive to rules and etiquette and value personal respect, while Vietnamese emphasize solidarity, pride and love for their homeland, he says. “These differences sometimes lead to conflict.”

Le Van Lam, 30, who lives in Aichi Prefecture, says learning Japanese and showing respect to locals are key to avoiding trouble and culture shock.

Every year on Sept. 2 he asks his landlord for permission to fly Vietnamese flags for National Day, explaining that they are a sacred symbol that honor those who sacrificed for Vietnam’s peace. This year he hung 300 small flags in his garden without receiving any negative reactions.

Some Japanese neighbors stopped by, praised the display, asked about its meaning, and toured the garden after he explained.