How to read the SHIZUAN map
SHIZUAN draws every neighborhood of mainland Tokyo as a column. Once you know what the height and color stand for, the map becomes much easier to read, and much harder to misread.
A quick word on Tokyo neighborhoods
Tokyo addresses are built from a ward or city (such as Shinjuku-ku or Musashino-shi), a town name, and usually a numbered block called a chome. “Nishishinjuku 2-chome” (西新宿二丁目) is the second block of Nishishinjuku; the map writes names the same way. These small units are what the police use to publish their numbers, so they are what SHIZUAN maps. The 23 special wards form the dense core of the city; the Tama area to the west is a mix of suburbs, towns and hills. English names on the map are romanized from Japan Post's readings. When no reliable reading exists, the name stays in Japanese instead of being guessed.
Three layers and the “Where to stay” view
The tabs at the bottom of the screen switch what the columns show.
- Street incidents adds up violent crimes, assaults and similar offenses, pickpocketing, bag snatching and theft of unattended belongings, then divides by the land area of the neighborhood. It describes the streets you walk on.
- Residential incidents adds burglary and vehicle and bicycle theft to the violent and assault categories and divides by the number of residents. It describes the surroundings of a home.
- Estimated quietness is a score from 0 to 100 calculated from zoning, late-night venues, major roads and railways, and station ridership. It is an estimate, not a noise measurement.
The map opens in Where to stay. Neighborhoods that glow in lamp color have relatively few street incidents, a higher quietness estimate, several places to stay nearby and a station within walking distance. You can adjust those conditions under “Filters & list” in the lower left.
What “reported incidents” means
The police in Japan publish ninchi kensu, the number of offenses they have become aware of, usually because someone reported them. Anything that was never reported is missing. The share of cases that get reported differs by type of offense, so the gap between reported and actual numbers varies too.
SHIZUAN does not treat every offense the same. Violent crimes such as murder and robbery count ten times; assaults and similar offenses count four times; pickpocketing and similar thefts count twice. The figures on the cards are “weighted incidents” for that reason. The full list of weights is on the Data & methods page.
Per km² and per resident give different answers
The same count can look very different depending on what you divide it by.
Per square kilometer (street incidents) rises wherever a lot of people pass through a small space: busy station fronts, shopping streets and nightlife districts. Few people may live there, but crowds of commuters and visitors raise the count. Spread-out residential suburbs come out low because their land area is large.
Per 1,000 residents (residential incidents) pushes those same central districts even higher, because their resident population is small. That is why neighborhoods with fewer than 100 residents do not get a residential figure at all.
Neither view is the right one on its own. If you want a sense of the streets you will walk at night as a visitor, the per-area layer is closer to that question. If you want to understand the area around a home, the per-resident layer is closer.
The baseline: the median neighborhood in Tokyo's 23 wards
The five colors (Very low, Low, Average, High, Very high) are ratios to one fixed baseline: the median neighborhood of Tokyo's 23 wards. Up to half the median is “Very low”; more than double is “Very high”.
The Tama area is colored against the same baseline. Much of it ends up “Very low”, largely because people are spread over far more land than in the 23 wards. We keep one yardstick on purpose. With separate baselines, two neighborhoods on either side of a city boundary could have the same figure and still get different colors.
Column height and the numbers on a card
Column height follows the selected layer on a logarithmic scale, with a cap so that a few extreme neighborhoods do not hide everything else. On the quietness layer, taller means livelier.
Tap any column to open its card. Next to the level you will see the rate, how many times the median it is, the area or population, and the three-year total. Small neighborhoods can move a lot with just a few cases, so look at the raw numbers as well as the color.
Easy ways to misread the map
- “Very high” does not directly tell you the chance that any one person there will be a victim. Places with more people simply collect more reports.
- A pale neighborhood does not mean zero incidents.
- Census boundaries do not always line up with postal addresses.
- Estimated quietness says nothing about a specific building's walls or windows.
Now try it on the map. If you are planning a trip, continue with choosing an area to stay; if you are relocating, see checking a neighborhood before you move.