Artefacts were on display at the Kaetsu Educational and Cultural Centre . Staff launched a search for the wooden plaque and replica textbook . They were loaned to the university by Okinawa's Peace Memorial Museum . The discovery of the book was made in December last year when staff from the museum found it among other items that had been left behind after an earthquake struck Japan in 2011.
Artefacts were on display at the Kaetsu Educational and Cultural Centre . Staff launched a search for the wooden plaque and replica textbook . They were loaned to the university by Okinawa's Peace Memorial Museum . Tourist returned the artefacts and offered an apology to staff .