| Municipal boundaries | National Land Numerical Information "Administrative Areas" (MLIT), simplified by smartnews-smri/japan-topography; detailed boundaries from the 2025 edition | January 2021 / January 1, 2025 |
| Population | Statistics Bureau of Japan, Population Census (basic tabulation) | 2025 |
| Area | Geospatial Information Authority of Japan (GSI), Area Statistics of Prefectures and Municipalities | 2025 |
| Railways and stations | National Land Numerical Information "Railway" data (MLIT) | 2024 |
| Station passengers | National Land Numerical Information "Passengers by Station" data (MLIT) | Fiscal year shown per station |
| Mountains, readings, station openings | Wikidata (CC0). Mountains of 800 m or higher; the 100 Famous Japanese Mountains are marked | |
| Official websites | Wikidata (CC0), "official website" | Linked when shown |
| Famous mountain and castle lists | Japanese Wikipedia list articles (CC BY-SA 4.0) and Wikidata (CC0); positions, elevations and photos from Wikidata | |
| River length, basin area, tributaries | Wikidata (CC0), mostly based on values published by MLIT and others | |
| Places to visit | Chosen automatically from Wikidata (CC0) items; photos from Wikimedia Commons (photographer and license on each photo) | Loaded when shown |
| English names | Wikidata English labels (CC0); otherwise romanized (modified Hepburn, no macrons) from the Japanese reading in Wikidata or Japanese Wikipedia | Retrieved November 2026 |
| Roadside stations (Michi-no-Eki) | Based on the MLIT "Michi-no-Eki" list (https://www.mlit.go.jp/road/Michi-no-Eki/list.html, Public Data License 1.0). Positions from Wikidata (CC0), otherwise OpenStreetMap (© OpenStreetMap contributors, ODbL) or the address | As of September 4, 2026 (1,234 stations) |
| Current weather (observations) | Japan Meteorological Agency (JMA) website (AMeDAS, latest observation data, high-resolution precipitation nowcasts). Preliminary observations shown unchanged, with station name and time | Loaded when shown |
| National park boundaries | Ministry of the Environment, Biodiversity Center of Japan, "National Park Areas" GIS data (https://www.biodic.go.jp/), combined and simplified by NIPPON ATLAS | Updated April 28, 2025 |
| National park area and designation dates | Ministry of the Environment, "Overview of National Parks" | April 10, 2026 |
| AMeDAS station for each municipality | Chosen by this site from the JMA AMeDAS station list (nearest stations in the same prefecture) | Retrieval date in site/jma_area.json |
| Earthquakes and tsunami warnings | JMA website "Earthquake information" and "Tsunami information", shown as issued | Latest when viewed (checked every 60 seconds) |
| Weather warnings and advisories | JMA website "Weather warnings and advisories", shown as issued | Latest when viewed (checked every 5 minutes) |
| Sunrise and sunset | Calculated (NOAA solar position equations); checked to agree within 1 minute with the National Astronomical Observatory of Japan | Calculated |