My own map of the underground would be pretty simple. Overland railway gets me to mainline stations in the centre of town from where I like to walk. But for travelling to Joanna at Archway, and to outlying galleries, I use the tube. Central to Chisenhale or the Serpentine; Bakerloo to Lisson; Jubilee to Saatchi's ... I draw my white lines: a horizontal crossed by a vertical and two near-verticals emerging from the same point. The rest is darkness.
Satomi Matoba's map is her own Utopia. Actually, it's Hawaii, but in a northern bay - on the other side of the island from Pearl Harbor, Honolulu and the tourist beaches - can be found Hiroshima. Computer technology has been used to seamlessly fuse the two originals to produce a hybrid, East and West existing side-by-side in an island in the middle of the Pacific, roughly equidistant between Japan and the rest of the United States.
This artist was born in Hiroshima, educated and trained in Japan, and is now furthering her art education in the UK. She is invigilating the show, so I ask her where the bomb fell on Hiroshima. She shows me. She also shows me where her mother-to-be was that day - only a couple of kilometres south of the city, protected from the atomic blast by the bulk of a hill. And where her future father was - in a rugged wooded area a few more kilometres away, I imagine them making their way towards one another, meeting, their joy in their mutual survival eclipsing - at least for a while - the sadness of the wider human tragedy that's engulfed their home city. I see the pair walk the few kilometres to the centre of Hawaii where there is a little village by a lake, and settle down to raise a family.
At home, I phone my parents and ask what they recall of August 6, 1945. Dad tells me he was doing basic infantry training at the time, with no access to newspapers and so was oblivious to what had taken place on the other side of the world. He recalls that on VJ day, a week or so after the bombs fell, he spent the national holiday away from barracks, quietly walking around Perth. I mentally superimpose the fair city of Perth on Pearl Harbor while I'm waiting for Mum to come to the phone. She reads from her diary of more than 50 years ago:
"August 6, Sunday. Hired a bus for the whole family, 18 of us. Great day on the beach playing games with the kids and grown-ups.
"August 13, Monday. I know I've missed a whole week but nothing much happened so I'll skip it. Waited all day for the announcement of the end of the war but it didn't come. So we went dancing.
"August 14, Tuesday. Another day of suspense and still no news at nine pm. But about one o'clock I was wakened out of my sleep with a terrific noise. Our door was nearly knocked over and we were informed the war was finished."
The war is finished. Celebration breaks out all around the island. An ecumenical service culminates in haiku; Sumo wrestlers participate in Highland Games; cheerleaders perform a Noh play; frolicking and reflection alternate from dawn to dusk ...
There is a single van Gogh painting in Honolulu's Academy of Arts. In the background are calm fields and a turquoise sky with billowing white clouds. In the foreground, wheatsheaves are stacked together. Atop the straw structure, yellow ears of corn explode with life, they sparkle and dance. Below, the bunched stalks have a grass-skirts look about them. Clearly, the painter was very much alive the summer when he made the picture, and treasured the rising sun.
The Hawaiian van Gogh. Everyone on the island just loves it.
Cable Street Gallery, E1 (0171 790 1309): ENDS TODAY.