Windward is the open almanac of the Tamagawa Children's Day Association — every koinobori station read like an instrument: wind speed, streamer count, the bloom of riverbank green, and the daylight that raises the carp.
The festival programme is published the way the almanac reads everything else — as a measured natural event. Wind rises through the morning, peaks for the noon raising, and eases toward the lantern-fold at dusk.
Every station on the river feeds the registry. The four headline readings are charted live; the wind-rose on each panel turns toward the prevailing bearing, the graduated arc marks the scale.
Steady west-southwest off the Tanzawa ridge. Ideal raising conditions, holding since dawn.
Across 37 stations — 92 more than the same hour last season. The black magoi lead every pole.
Leaf-out along the banks, measured against the ten-year median. The green is two days ahead.
The registry keeps an open ledger — measured columns in mono, region names in serif, hairline dividers, each row tagged with a small status dial. No heavy rules; the page reads like a well-set reference table.
| Station / village | Wind (m/s) | Streamers | Tallest (m) | Bloom | Reading |
|---|---|---|---|---|---|
| Setagaya · bank 4 | 4.6 | 214 | 9.0 | 81% | Strong & steady |
| Nakameguro · weir | 3.1 | 168 | 7.5 | 74% | Gentle rise |
| Chōfu · gravel flat | 5.2 | 240 | 10.0 | 88% | Strong & steady |
| Komae · footbridge | 2.4 | 96 | 6.0 | 69% | Light · watch |
| Tamagawa · banks 1–2 | 4.0 | 302 | 8.5 | 79% | Strong & steady |
Any household, school, or ward can enroll a streamer station. Your readings join the open almanac; your poles appear on the live map. Three memberships, one squared form.
Kodomo no Hi has marked the fifth of May for centuries — carp climbing the wind as a wish for a child's resolve. The Tamagawa Association reads that wish as data: not to dim the festival, but to keep it honestly, year over year.
Every enrolled station logs four measures at fixed intervals — wind speed and bearing from a calibrated cup anemometer, the count and tallest height of raised streamers, and the riverbank leaf-out scored against a decade of photographs. Each reading is timestamped, attributed to a station, and published open. Nothing is smoothed away; a quiet morning reads as a quiet morning.
The wind-rose you see on every panel is the association's instrument: a graduated dial that turns toward the prevailing bearing so a glance tells you which way the carp are flying, and how hard. It is the same dial in the registry, the ledger, and the printed plate.
Six banks of the Tamagawa carry the festival, each with its own dial. The map is the registry's chart — find a station, read its wind, walk to its poles.
At dusk the dials are read one last time and the day is sealed into the almanac — a charted retrospective for every household, every ward, the whole river. Next year's curve begins where this one closed.