It's midnight in Akasaka's second chōme block, situated near the northern edge of Minato City, Tokyo. On the 5th floor of the Akasaka Sannō Kaikan building, Mājānya, a nocturnal Mahjong parlour, begins its nightly closure after a day filled with the clamour of Mahjong tiles and a lunchtime curry service. Imagine the intensity of lunching on curry rice whilst Mahjong battles play out all around. An hour or so earlier, a throng of men emerged from the basement’s live house, buoyed by an electrifying J-pop idol showcase. Much glowstick waving was had to impassioned performances by emerging starlets of the idol underground.

With the arrival of morning, sharply suited employees of the Mita Corporation, an estate agent established in the 1960s, will start to fill the building's 7th and 9th floors for another day spent matching apartment-hunting Tokyoites with rental properties. Slotted between them on the 8th floor, the fashion-forward stylists at Salon Ryu ensure Tokyo's young professional women remain impeccably coiffed, attending to every strand of hair with precision. Down on the 3rd floor, the Akasaka branch of Goo-it massage clinic readies itself to offer relief to Minato City's elderly.

Later that day, the building's restaurants will begin to warm their kitchens and display their kanban signs. The fast-food steak chain Ikinari dishes out searing hotplates of cut steak and rice to hungry salarymen. In contrast, Sumiyaki Ryōri Hayashi offers a rustic ambiance with its traditional sunken hearth and charcoal fire, serving some of the city's finest oyakodon. Concealed on the fourth floor of what might be mistaken for a weathered, nondescript office block—a bland, glass-fronted cubic structure with grey cladding and no distinctive features—exists this homely restaurant, more akin to the inside of a UNESCO-listed thatched cottage in the countryside.

That might have escalated quickly, but the activities of the Akasaka Sannō Kaikan building are typical of those found across Tokyo in similarly occupied multi-storey buildings. A cacophony of businesses, stacked one atop the other, conducting unrelated trades, attracting a diverse clientele. I'd like to remove the glass facade of a building like Sannō Kaikan to reveal its intricate internal dynamics, like a 3D cross-section diagram.