Empress emerita Michiko received greetings from her relatives and palace officials to celebrate her 90th birthday Sunday as she steadily recovers from a broken leg, officials said.

Michiko is the first commoner to become empress in modern Japanese history. Catholic-educated Michiko Shoda and then-Crown Prince Akihito married on April 10, 1959, after what is known as their tennis court romance.

The couple retired after Akihito abdicated in 2019 as their son, Emperor Naruhito, ascended the Chrysanthemum Throne and his wife, Masako, became empress.

Since then, Emperor emeritus Akihito and Michiko have largely withdrawn from public appearance to enjoy their quiet life together, taking daily walks inside the palace gardens or occasionally taking private trips, hosting small gatherings for book reading and music, according to the Imperial Household Agency.

Akihito has been concerned about Michiko’s physical strength and asking how she is feeling, officials said.

Michiko, who fell earlier in October at her residence and had a surgery for her femoral fracture, was steadily recovering with a daily rehabilitation session for about an hour at a time, palace officials said. She was expected to be in a wheelchair when joining her well-wishers for Sunday’s celebration.

The former empress was deeply concerned about the people affected by the deadly Jan. 1 earthquake in Japan’s north-central region of Noto, especially those who suffered additional damage from September's heavy rains and floods, the palace said.

Since retirement, Michiko has shared her love of literature, including children’s books, English poetry and music, with her friends as well as with Akihito.

The palace said she reads parts of a book aloud with her husband as a daily routine after breakfast. They are currently reading a book chosen by Akihito about war and Okinawa, a southern Japanese island where one of the harshest ground battles took place at the end of World War II fought in the name of his father.

The couple broke with traditions and brought many changes to the monarchy: They chose to raise their three children themselves, spoke more often to the public, and made amends for war victims in and outside Japan. Their close interactions have won them deep affection among Japanese.