The pair are in the Japan squad that will compete at the AFC Women’s Asian Cup in Australia, which runs from March 1 to March 21.
Japan kick off their schedule against Chinese Taipei in Perth on Wednesday (March 4) and will also face India and Vietnam in their group.
As a result, Nagano and Shimizu are set to be absent for the Reds’ Barclays Women’s Super League fixtures against Leicester City and Brighton & Hove Albion.
“Of course it will be sad to be missing for my club, but for Japan the Asian Cup is a very important competition,” said Nagano.
“We have to show our quality and that we are the strongest team in Asia and win this competition. It is still summer in Australia so it might be a bit warmer than it has been here recently, so I can’t wait to experience the warmer weather again!”
She added: “I’m excited for this tournament and I want to give it everything and enjoy the competition as much as I can.
“It would be a special moment if we lift up the trophy.”