What will become of shrine's souls?
How do you find a single drop in a pool of water?
As Japan's neighbours brace for Prime Minister Junichiro Koizumi's expected visit to the Yasukuni Shrine today, that question is at the core of debate about its future.
A visit today by Mr Koizumi would be his first on the sensitive anniversary of Japan's surrender at the end of the second world war 61 years ago. It would lmost certainly be his last visit as prime minister - capping a tenure in part defined by international concern over Yasukuni, where the spirits of 14 executed class-A war criminals from the second world war are honoured along with 2.5 million other war dead.
The Japanese elite is wondering how to finally resolve the Yasukuni issue, given the growing weight of its historical and diplomatic baggage.
Just yesterday, a former vice-president in Mr Koizumi's ruling Liberal Democratic Party called for the 14 war criminals to be honoured separately. Taku Yamasaki, who is considered a confidant of Mr Koizumi, said on national television that this would allow the emperor to visit the shrine, and would 'drastically change' concerns in China and South Korea, both victims of Japan's wartime brutality.
His comments follow several similar calls, from pugnacious Minister of Foreign Affairs Taro Aso, business lobbies and others, for a new approach to Yasukuni. One problem is that it is not government property. And the Shinto priests who manage the shrine have long stated that the names honoured within in are all part of a 'pool of souls' - meaning no single name can be removed.
Senior foreign ministry officials echo this line as they struggle for understanding from Japan's neighbours over the prime minister's repeated visits. 'Under Shinto beliefs ... to remove a single soul would be like trying to recover a drop from a pool of water,' one official said.
The leader likely to have to move the debate on is Chief Cabinet Secretary Shinzo Abe, the man tipped to replace Mr Koizumi as party chief next month.
Mr Abe, an enthusiastic shrine visitor in the past, has so far dodged questions over Yasukuni's future.
'Koizumi's bringing it all to a head and leaving for it for Abe to solve,' said one European diplomat. 'It's gone beyond just the issue of a visit ... something's got to be done - that's the current mood. Domestically it would be tough for the government to act over Yasukuni, given issues of private property, religion and civil liberties,' he said.
China and South Korea are monitoring developments, but envoys have stopped short of stating that formal visits by senior officials are unacceptable.