Bishop Alexis Shirahama of Hiroshima, Japan, has opened a 75-hour vigil for peace marking the 81st anniversary of the atomic bombing of the city.

The event involves a prayer relay linking Hiroshima to Nagasaki, Rome, and New York.

The Diocese of Hiroshima offered a Mass for the victims of the bomb and all war dead at 8 a.m. Thursday local time at the World Peace Memorial Cathedral in the cityʼs Noboricho district, the hour the diocese gathers each year, minutes after the 1945 blast.

The vigil, organized with the Community of SantʼEgidio — the Rome-based lay movement known for its peace diplomacy — runs until exactly 11:02 a.m. on Sunday, the very minute the second atomic bomb struck Nagasaki, according to the diocese.

The Focolare Movement, parishioners, and volunteers are taking part. SantʼEgidio has kept the vigil annually since 2022.

The day, Aug. 6, is also the feast of the Transfiguration.

The Japanese prelate and the SantʼEgidio president, Marco Impagliazzo, issued a joint message to link the commemoration with the call for the common good as set out in Pope Leoʼs first encyclical, Magnifica Humanitas.

In the message, Shirahama and Impagliazzo reflected on the American pontiffʼs words, calling the vigil a way to receive the peace of the risen Christ, “a disarming, humble, and persevering peace” — the phrase Leo used from the loggia of St. Peterʼs Basilica minutes after his election in May 2025.

Three chapels are open to the public for this event: the crypt of the cathedral in Hiroshima, the Chapel of the Sacred Hearts of Jesus and Mary in New York, and the Basilica of Santa Maria in Trastevere in Rome.

The prayer is livestreamed, and organizers are reading aloud intentions sent in from around the world.

Thursday also marks the beginning of the annual “Ten Days for Peace” for Japanese Catholics, an event of prayer and penance running from the day of the Hiroshima bombing to the date of Japanʼs surrender on Aug. 15.

The bishops began the observance after Pope John Paul II came to Hiroshima in 1981 and issued his Appeal for Peace, telling the world that to remember the city is to repudiate nuclear war.

Pope Benedict XVI, in his 2006 World Day of Peace message, called reliance on nuclear arms “not only baneful but also completely fallacious,” warning that in a nuclear war there would be “no victors, only victims.”

Pope Leo, in a foreword published in July, called for the elimination of nuclear weapons outright.