Japan’s diplomatic relations with the Vatican date back to the arrival of Francis Xavier (1502–1552) and the subsequent history of the hidden Christians. This is not remembered by the Vatican as a history critical of Japan’s persecution of Catholics, but rather as a story of believers who, despite harsh oppression, remained in hiding for centuries to protect their faith. The year 2025 is a Holy Year in Catholicism and also marks the 440th anniversary of the Tensho Embassy’s audience with the pope. A commemorative Mass, which your correspondent attended, was held at a Roman church that Nakaura Julian (1568–1632) once visited. In addition, a famous portrait of Ito Mancio (1568–1632) painted by Tintoretto (1518–1594) is currently on display at the Holy See Pavilion (hosted by Italy) at the Osaka Expo 2025. Although it might be tempting to dismiss these events as occurring over 400 years ago, the Vatican itself has a 2,000-year history. The first pope was St. Peter, one of the twelve apostles of Christ, and the newly elected Pope Leo XIV, inaugurated on May 8, 2025, is the 267th pope. Without a long historical perspective, one cannot full understand the nature of Vatican diplomacy.
The fact that Nagasaki and Amakusa, the areas in Kyushu where many hidden Christians once lived, were registered in 2018 as World Heritage Sites related to the Hidden Christians is evidence of the salience of this history. While this was largely thanks to the efforts of locals, the Vatican is said to have also offered its support.
Pope Leo XIV is a member of the Order of Saint Augustine, the oldest monastic order, and as Prior General of the order, he attended a beatification ceremony held in Nagasaki in 2008. During that visit, he stayed at the monastery on the grounds of Shiroyama Catholic Church, the order’s headquarters in Japan, and went on a pilgrimage to the Sotome area of Nagasaki together with Japanese members of the order. These details cannot be overlooked, as they could influence the question of whether the new Pope will visit Japan. If he does return, his trip will likely include Nagasaki, one of the cities bombed with an atomic weapon, possibly followed by Hiroshima. The new Pope is following in the footsteps of his predecessor in many ways, making it highly likely that he will follow the same path Pope Francis took when visiting Japan. Though the current Pope has not made any remarks about nuclear weapons, he has expressed a willingness to mediate peace between Ukraine and Russia. He has also worked to facilitate an exchange of prisoners between the two countries, continuing the neutral role his predecessor played. With Russian nuclear threats and past heightened tensions between India and Pakistan, two countries with nuclear weapons, the Holy See, as a participant in the IAEA, may look to Japan, the only country to have suffered nuclear attacks.
Another important element in Japan’s diplomacy with the Vatican is the enduring presence in modern times of emperors and popes. A Vatican envoy was sent to Japan in 1919, and in 1921, then-Crown Prince (1901–1989), later Emperor Showa, had an audience with Pope Benedict XV while touring Europe at the invitation of the British government. During that meeting, they discussed the ongoing war and exchanged views on the Korean Peninsula, which was a Japanese colony at the time. Japan also considered sending a diplomatic envoy of its own to the Vatican. However, the Buddhist community in Japan opposed this plan, and with pressure mounting on members of the Diet, the proposal failed to pass because of a lack of budget approval. The tide turned following the outbreak of World War II in the Pacific, and Emperor Showa’s intervention led to the establishment of formal diplomatic relations between Japan and the Holy See in 1942. Remembering the experience he had at age 20, the Emperor saw the benefits of a diplomatic channel with the neutral Vatican during the Pacific War, and dispatched a special envoy Harada Ken (Ambassador status). As a neutral party, the Vatican then worked to bring peace through an early end to the war between Japan and the U.S.
These efforts were ultimately unsuccessful, and the conflict continued until the atomic bombings of Hiroshima and Nagasaki. However, they did play an important role in rebuilding postwar relations between Japan and the Vatican. During the Allied occupation of Japan, the Vatican sought to prevent any overly harsh punishment of Japan, working through the Catholic Church in the U.S. While this may have been influenced in part by Catholic teachings on mercy and forgiveness, it was also shaped by the political situation in neighboring China and on the Korean Peninsula.
The Vatican established diplomatic relations with China during the Qing Dynasty, but following the Communist Revolution, all religions, including Christianity, were suppressed, and diplomatic relations were severed in 1951. After the outbreak of the Korean War, many Christians were killed in North Korea. Based on the situation in neighboring countries, the Vatican realized that the preservation of the Emperor System in postwar Japan could act as a safeguard against the rise of Communism. When Japan regained its sovereignty under the San Francisco Peace Treaty in 1952, Pope Pius XII sent a congratulatory letter to Emperor Showa, along with a message to Crown Prince Akihito on his coming of age. During a papal visit to Japan in 1981, Emperor Showa met with Pope John Paul II directly, and the current Emperor also met with the same Pope while he was Crown Prince. When Pope Francis visited Japan in 2019, he was welcomed by the current Emperor, and upon the Pope’s passing, Prince Akishino attended the funeral mass as the Emperor’s personal representative. Politician Aso Taro also attended the ceremony for Pope Leo XIV’s inauguration.
Pope Leo XIV has not yet scheduled a visit to Japan, but he has many ties to the country, including his pilgrimage to Nagasaki related to the history of the hidden Christians, his interest in peace mediation and nuclear disarmament in war and conflict, and his interactions with emperors and popes in the past. As an American, his potential relationship with U.S. President Donald Trump is drawing attention, and expectations are growing in Japan that he may help maintain strong U.S.-Japan relations. It has also been reported that the new Pope interacted with the Japanese Catholic community in his “second home” of Peru, where he holds dual citizenship and spent around two decades engaged in poverty relief work. With all this in mind, Japan eagerly awaits a possible visit from Pope Leo XIV in the coming years.
MATSUMOTO Saho is a professor at the College of International Relations Department of International Liberal Arts, Nihon University.
