In the courtyard of Tomioka Hachiman Shrine stands a statue of a hero of mine: Inō Tadataka (1745–1818). Inō worked as a sake merchant and village head during the late Edo Period until retiring to study calendrical science at the age of 49. I admire this steely midlife career change. It was a productive choice—his studies led him to survey all of Japan. At 56, Inō embarked on a 17-year journey to map the country’s coastlines and highways, meticulously measuring his steps and conducting astronomical observations throughout.

Initially, the survey was a personal undertaking, but it gained official recognition after Inō presented his work to Tokugawa Ienari, the shogun at the time. About 80% of the project was eventually funded by the shogun—the best investor one could hope for in Edo Japan. The output became a set of maps, with each sheet approximately the size of a tatami mat. The complete set of 214 sheets depicted the entire Japanese archipelago, marking Japan's first nationwide survey based on actual measurements.

When Inō died at 73, he left the final segments unfinished, but the Astronomical Bureau completed the project in 1821, releasing it as the Dainihon Enkai Yochi Zenzu, meaning 'Comprehensive Map of Japan's Coastal Areas'. Better known as the Inō-zu, or the 'Inō Maps', it was the first geographically accurate depiction of Japan, presenting the unmistakable silhouette we know today.

Inō lived in Fukagawa Kuroe-chō, which is now part of the first chōme of modern-day Monzen-Nakachō in Kōtō-ku. This connection explains why his statue stands in the ward’s Tomioka Hachiman Shrine. Inō's story felt especially relevant as I walked his former locale, jotting down notes and marking pins on my map to prepare for this area guide. Indeed, it has been some time, but today, we walk.

Our exploration begins late afternoon on a bright but hazy Saturday at Exit 1 of Monzen-Nakachō metro station. Traffic moves swiftly along the wide Eitai-dōri thoroughfare, but the air feels calm. The afternoon stretches ahead of us, with the evening still to come. We are now in Tomioka 1-chōme, and to the east, Monzen-Nakachō spans two chōme blocks. These administrative divisions, part of the greater Fukagawa area, flank both sides of Eitai-dōri.

I often enjoy starting a walk with a counterintuitive route, but today's itinerary is a day-to-night journey with destinations that depend on timing. With that in mind, we'll begin by immediately passing beneath the bold and striking gate to the right of Exit 1. It resembles a kabukimon, a roofless gate characterised by a horizontal beam spanning its posts. Although such gates are typically left in their natural wood finish, this one stands out with its vivid red colour and Chinese-inspired embellishments. Kabukimon are usually associated with Buddhist temples rather than Shinto shrines, and the name Naritasan (成田山), shown on the central plaque, confirms its connection to Naritasan Shinshōji Temple, a prominent Buddhist temple in Narita.