But he got through the day somehow, smiling and nodding and waving away their requests for photographs. And besides, his determination to complete the mission he had set himself would carry him through.

He walked the mile or so south from the Tokyo JR station to Ginza, the most famous entertainment and shopping district in Japan — so he had been told; he’d never been here before. What he found was an oddly American-flavoured district of glittering, high-rise buildings laid out on a rectangular street pattern, neon signs bright enough to dazzle even by day.

Everywhere was crowded, of course, but without the sense of crush and bustle he’d grown up with in Dublin, even London; that, of course, was because of the Japanese habit of politeness and deference, all that smiling and bowing that had seemed so odd to him at first, but which now he understood as a vital social lubricant, the only way so many people could get along on this cramped little island chain.

Politeness and deference — from everyone except the school kids, attracted endlessly by the gaijin mask he could never take off.

And it was in Ginza — in a small (but expensive) shop near the Sony Building — that he found what he was looking for.

In amongst the trashy Buddhist charms and plastic fans and pictures of twelve-year-old pop stars, there was row on row of vials of ash-grey dust: rock from Edinburgh. Each vial, he found, came with a certificate of authenticity from some geology institute he’d never heard of, and a list of the uses to which people were putting this stuff. Scattering it over their Zen gardens. Putting it in their Shinto shrines. Even mixing it with milk and drinking it.

For this anonymous-looking volcanic ash had been — if the stories were true, if the ash were genuine — transformed by the ghostly touch of the Moon itself.

Declan bought three vials. Then he turned and, without hesitation, made his way back to the JR station.

Home for Declan, for the last decade, had been a small Shinto shrine called Futaarasan, which stood on the north bank of Lake Chuzenji, some hundred miles north of Tokyo. Now he retraced his journey to Futaarasan, taking the Shinkansen bullet train from the capital to Nikko, and the bus to Chuzenji.

At last, cradling his vials, Declan made his patient way back along the lake’s north shore road towards the shrine.

Chuzenji was once, probably, an attractive area, he thought. But the town had become a trashy resort, feeding off the cable-car that took visitors down the river gorge to see the Kegon Waterfall. Through the trees that lined the lake, he could see pleasure boats made absurdly in the shape of swans, Disney-style, plying back and forth.