Researchers resumed on Monday their probe of the ancient Kitora tomb in Asuka, Nara Prefecture, after halting the work for more than two years.
The plastered and painted walls in the stone chamber of the tomb, which dates from the late seventh to early eighth centuries, have appeared close to coming off since their discovery via a fiberscope camera in 1983. Researchers say it is vital that restoration work start soon.
There is speculation that someone related to seventh-century Emperor Tenmu, under whom law codes known as the Ritsuryo system were adopted, lies in the tomb.