Monsignor Cesare Pasini, head of the Vatican's Apostolic Library, said
the so-called Marega Papers represent the largest known civic archive of
its kind.
An Italian missionary priest took the 22 bundles of documents
out of Japan in the 1940s and brought them to Rome.
They sat in the
Vatican library's storage depository for decades until a Vatican
researcher who could read the characters realized their importance in
2010.
The six-year agreement signed Tuesday to inventory the documents and
prepare them for study involves the National Institute of Japanese
Literature and National Museum of Japanese History, among others.