Authorities in Hiroshima have asked the game developer behind Pokémon Go to take action as players descend on the city's atomic bomb memorial park.
They have asked Niantic to remove "Pokestops" and other virtual sites that show up in the park for those playing the augmented-reality game.
The western Japanese city wants them deleted by August 6, the anniversary of the 1945 bombing and the date of an annual ceremony to remember the victims.
Niantic declined to comment, saying it would not make public any discussions with a third party.
The expansive Hiroshima Peace Memorial Park is meant as a solemn memorial to the victims, but it has become a draw for players since the Japanese release of the addictive smartphone game last Friday.
Elsewhere, the US Holocaust Memorial Museum in Washington DC and nearby Arlington National Cemetery have made similar requests to Niantic.
Holocaust museum spokesman Andrew Hollinger said on Wednesday that the museum had been removed from the game according to its wishes.
Niantic offers a form to request exclusions, but it is neither automatic nor guaranteed.
The location-aware app gives digital rewards for visiting real places that have been designated Pokestops and Gyms in the game.