Koto-ku

In the most recent Population Census the population is about 524,000 (524,310 in 2020). Over the five years from 498,109 in 2015 it added twenty-six thousand. Even among the 23 wards, it is a ward that has clearly grown its population.

What is worth seeing here is that the number of children is rising too. Those under 15 rose from 62,350 (2015) to 66,472 (2020), some four thousand more. Wards whose absolute number of children is rising are not many across the 23. Over the same period the share aged 65 and over moved nearly flat, from 21.1% to 21.0%, on the gentle side of aging among the 23 wards. Households with children make up 19.0% (2020), thicker than Taito-ku’s 11.9% and Sumida-ku’s 14.7% along the same Sumida River. The residential land price is around 697,000 yen per m². The Fiscal Capacity Index is 0.50, below 1.0, because the special wards pool part of their municipal taxes at the metropolitan level and have them redistributed through the Tokyo Metropolitan–Ward Financial Adjustment System; as a ward-alone figure it settles at this level. The childcare waitlist is 0 children (2025). Why the upward trend is clearest here among the three riverside wards: on land made by filling the sea, canals and factories lined up, and that shipyard site opened in consolidated tens of hectares and turned to housing — that one great turn ties these figures into a single thread.

Koto-ku’s skeleton is the very land made by filling sea and low wetland by human hands. The ward became a single administrative body after the war, formed in 1947 by the merger of the former Fukagawa Ward and Joto Ward; candidate names are said to have included Tatsumi, Higashi and Eitai. This ward’s development begins with early-Edo reclamation. In Ieyasu’s time the Onagi-gawa canal was opened, and Fukagawa village rose from the development of new fields by drainage around it.

The foundation was water transport. Through a network of canals laid out lengthwise and crosswise, this area became a logistics base of Edo–Tokyo, and above all played the role of timber ponds where lumber was stored — developing as a town that carried and stored goods by river and canal. Meanwhile the Joto side — Kameido, Ojima, Sunamachi — grew as a factory belt, and through the municipal system of 1889 was incorporated into Tokyo City in 1932 as Joto Ward. The logistics of the canals and the factories of Joto: logistics and industry layered atop the water.

And one more reclaimed area greatly moved this ward’s present. Toyosu was reclaimed from late Taisho into early Showa and named “Toyosu” in 1937. In 1939 the new plant of the Tokyo Ishikawajima Shipyard was placed there, and it became a town of shipbuilding. But in the 1990s Ishikawajima-Harima Heavy Industries — today’s IHI — withdrew from shipbuilding, and the Toyosu plant closed in 2002. On the site, land-readjustment work advanced, and with the town’s opening in 2006 came a Yurikamome station and large commercial facilities; the factory site was remade into a town of housing and commerce. Reclamation, canals, timber ponds, shipbuilding, and the redevelopment of a factory site — this town’s form is the record of stacking each era’s function atop land made by filling the sea.

What characterizes Koto-ku is that, while the population rose by twenty-six thousand, the number of children rose by some four thousand. That appears in the figures for living conditions in a form of addition and enrichment, opposite to the consolidations common in regional cities that lost large populations. Households with children make up 19.0%, clearly thicker than Taito-ku and Sumida-ku along the same Sumida River. Housing born from the redevelopment of factory sites has gathered households with children.

The childcare waitlist is 0 children. A zero waitlist in a town where children keep rising is opposite in meaning to the “zero from a thinned absolute number of children” common in regional cities of population decline. It is a zero reached by fully bringing supply abreast of demand while children and population both grow — a consequence of widening capacity for rising children and keeping supply and demand in balance. Read the same “zero waitlist,” and how it reads changes entirely with whether children behind it are rising or thinning. Children increase, the waitlist hits zero — Koto’s living-conditions figures read straight as the consequence of reclaimed land deepening its thickness as a place to live.

Koto-ku holds several functions of its own. One is the canal network laid out since early Edo, which once supported a town of logistics and timber storage and still runs lengthwise and crosswise through the ward as waterfront. Another is the waterfront reclaimed land, Toyosu among it, where redevelopment of factory sites such as shipyards brought a clustering of housing and commerce. Further, the Joto side — Kameido, Ojima, Sunamachi — holds urban land that developed as a factory belt.

Koto has shifted, atop the same land made by filling sea and low wetland, from the logistics of canals to industry, and on to housing and commerce. From a town of timber ponds and shipbuilding, through redevelopment of factory sites, to a place to live that increases its population children and all — the condition of “waterfront land made by filling” has carried different functions, era by era. The canals, the factories and the redeveloped housing alike rest, in the end, on the same condition: land filled by human hands. Atop ground made by filling the sea, logistics gave way to industry, industry to housing — Koto-ku is that contiguous remaking.