FOR centuries the wako, dastardly Japanese pirates, skulked in the countless coves of Tsushima island, roughly halfway between the Japanese archipelago and the Korean peninsula, frequently raiding the coast of Korea. In 1592 General Toyotomi Hideyoshi and his 200,000 men launched the seven-year Imjin invasion from the island, landing in Busan, on Korea’s southern coast. Centuries earlier sueki ceramics, a new form of pottery, had been transmitted from Korea to Japan via Tsushima.

Today it is mainly leisure-seekers who take the hour-long ferry ride from Busan to Tsushima: fishermen, hikers and day-tripping teens. Once a year, however, a delegation of South Koreans dressed in the colourful garb of 17th-century envoys makes the crossing. They are re-enacting the Joseon tongsinsa missions, or “sharing of good faith from Joseon” (an ancient name for Korea), which began in the aftermath of the Imjin war to reaffirm friendly ties between the Korean king and the Japanese shogun.

The envoys travelled along a 2,000km route, from Hanyang, as Seoul was then known, to Edo, present-day Tokyo, via Busan and Tsushima. The emissaries carried notes of friendship, and a dazzling assortment of Korean artwork. Over two centuries, a dozen such expeditions sent poets, painters, acrobats and calligraphers from Korea to Japan; by the time the delegations embarked from Busan, they had about 400 artists in tow. Another 1,800 joined them on the Japanese side. Villagers lined the streets to greet them, waiting up all night to receive a poem or painting.

The two governments are a long way from such cordial exchanges today. In the open sea north-east of Tsushima, they squabble over a group of rocks (Dokdo to South Koreans and Takeshima to the Japanese), and bicker with each other about history. Japan annexed Korea in 1910 and exploited it ruthlessly until 1945; many South Koreans feel Japan has done too little to atone for its colonial atrocities.

Among the most painful incidents for South Koreans is the corralling of tens of thousands of women into Japanese military brothels. South Korean civic groups erected a bronze statue of a “comfort woman” outside the Japanese embassy in Seoul in 2011, to serve as a daily rebuke to the diplomats inside. In December a similar statue was installed outside the Japanese consulate in Busan. In a huff, Japan’s government, which thought it had put the matter to rest by agreeing to compensate the surviving comfort women in 2015, recalled its ambassador to Seoul as well as its consul-general in Busan. Neither has yet returned to his post.

The spat also threatened to upset the centuries-long exchange between Busan and its Japanese sister city, Fukuoka, which lies roughly 200km across the Tsushima strait. Both cities are closer to each other than to their respective capitals. In the 1960s the people of Busan found it easier to receive Japanese TV signals than those broadcast from Seoul. Karaoke machines, now a staple in both nations, first came to South Korea via Busan, in the 1980s.

Last year a record 1.2m South Koreans travelled by ferry to Kyushu, the island of which Fukuoka is the main city, for its shopping, food and onsen (hot springs). Flights between Busan and Fukuoka have doubled since 2010, to eight round-trips a day. Akihiko Fukushima of the government of Fukuoka prefecture says that Busan is geta-baki de iku: close enough to visit in casual wooden slippers, as if popping round to see the neighbour.

Exchanges have remained remarkably resilient, despite the visit in 2012 of Lee Myung-bak, the president of South Korea at the time, to Dokdo, which sent diplomatic relations into a tailspin. That year the Fukuoka Asia Collection, an annual fashion show, invited designers from Busan, and still does (Busan returns the favour at an equivalent event). Foundations on both sides have worked on a joint submission of historical documents chronicling the Joseon tongsinsa for UNESCO. Journalists at Busan Daily and Nishinippon Shimbun in Fukuoka participate in an exchange programme—remarkable in countries where the media routinely peddle a nationalist line.

Idol threats

In 2013 it was a local stand-off that threatened to end for good the raucous jamboree on Tsushima that honours the missions. The previous year South Korean thieves had stolen a small 14th-century statue, thought to have been made in Korea, from the tiny temple of Kannonji on the island. The South Korean police recovered it soon afterwards. But a local court blocked the statue’s return to Tsushima, on the grounds that it had probably been pillaged centuries ago by the wako from a South Korean temple that was suddenly demanding its return. Incensed, the islanders told the Korean contingent to the festival not to bother coming. But the Japanese went ahead with the commemorations by themselves; one participant was Akie Abe, Japan’s First Lady, who claims to keep a special fridge just for kimchi, the pickled cabbage that is Korea’s national dish. And in 2014, when the visitors from Busan called for the statue’s return, Tsushima allowed the festival to go ahead again, despite protests from Japanese nationalists.

Last year the Bokchon museum in Busan celebrated two decades of exchanging artefacts with museums in Fukuoka, free of charge. A curator says such swaps would be impossible without personal friendships and trust. Sekko Tanaka, the retired chief monk of Kannonji, says he feels “betrayed” by the court. Still, he welcomes South Korean tourists to the temple’s guesthouse.

Japanese diplomats say they watch such exchanges as a more accurate measure of popular sentiment towards South Korea than strident press clippings and noisy protests organised by nationalist groups. The islanders of Tsushima, unlike other Japanese, use chingu, a word borrowed from Korean, to mean a close friend. South Korean visitors are charmed to hear that, on the clearest of days, the shoreline of Busan can be spotted; only a few spoilsports insist the sightings are, in fact, just a mirage.