The New York City Landmarks Preservation Commission announced today that it would give protected designation to the modernist box that houses the Japan Society. Built in 1971 and designed by the architects Junzo Yoshimura and George Shimamoto, it is now the city’s youngest landmark. (The previous youngest was the Ford Foundation’s home, which was built in 1967.) Also approved yesterday were the Renaissance Revival Engineers’ Club Building on 40th Street in midtown, the Neighborhood Playhouse on Grand and Pitt Streets on the Lower East Side, and the 1868 Greyston Gatehouse cottage in Riverdale. The last, “one of New York City’s finest examples of the picturesque royal cottage style that was popularized in the mid 19th century,” was actually an outbuilding to a larger manor house that was landmarked back in 1977.