Choose the observer on the map

To find out whether you can see it from a place you are going to (rather than where you are now), choose the observer (the place you watch the Diamond from) on the map. You can also search for a place or building by name and move the map there.

This article uses the observation lounge on the 25th floor of Bunkyo Civic Center (Bunkyo City Office) in Tokyo as an example and finds Diamond Fuji from there. The lounge floor is 105 m above the ground.

Note

At the time this guide was written (October 2026), the observation lounge of Bunkyo Civic Center is closed. Check that it is open before you go.

Steps

1. Press “Start the easy calculation”, then press “Pick on the map” under “Where will you watch from?”.

   

2. The map opens full screen. Press the magnifying glass button at the top left and search by place or building name. Place names are searched in Japanese; buildings can also be found by their English names. Here, we enter “Bunkyo Civic Center”. Press the place you want in the list, and the map moves there.

   

3. Tap the spot on the map that you want as the observer, and a blue pin is placed there. You can drag the pin to adjust it. Here, we place the pin on the west side of the observation lounge, which faces Mt. Fuji. When the position is right, press “Use this location”.

   

4. Under “What kind of place is it?”, press “Observation deck / tower”, enter the height of the deck floor (above the ground), and press “Next”. Here, we enter “105”. The app adds 1.5 m for eye level and calculates with 106.5 m.

   

5. Answer whether to save the place as a bookmark. Here, we enter “Bunkyo Civic Center 25F (west side)” and save it.

6. Press “Mt. Fuji” under “What will you look at?” and “Diamond” under “Sun or moon?”, and the calculation starts.

Ground elevation and height above ground

The height of the observer is the “ground elevation” plus the “height above ground”.

• Ground elevation: The elevation of the ground where you placed the pin. It is filled in automatically from the data of the Geospatial Information Authority of Japan.
• Height above ground: The height from the ground to your eyes. On the ground it is 1.5 m (eye level); on an observation deck it is the floor height plus 1.5 m.

Watching from a high place slightly changes the date and time when the sun lines up with the summit of Mt. Fuji. When you watch from an observation deck or the top of a building, enter the height correctly.

In the “① Observer (where you watch from)” panel, you can check the ground elevation and the height above ground below the map.

Tip

When you watch from a window, balcony or rooftop of an apartment building or similar, choose “Window, balcony or rooftop” under “What kind of place is it?” and answer the floor. The app calculates the height at 3 m per floor.

Calling up a bookmark

Next time, choose “From bookmarks” under “Where will you watch from?” to call up an observer you saved. The height is saved with it, so you don’t need to enter it again.

Troubleshooting

• The search finds nothing: Place names are searched in Japanese. Buildings can also be found by the names of registered skyscrapers. If you can’t find it, search for a nearby station or place, then move the map to find the spot.

Note

The app does not consider whether buildings, trees, etc. in front block the view. Check on site that you can actually see Mt. Fuji.

Caution

Never look directly at the sun, or at the sun through binoculars, a telescope or a camera viewfinder. It can damage your eyes. When observing, stay out of restricted or dangerous places and watch out for your surroundings and traffic.

Summary

Choose “Pick on the map” under “Where will you watch from?” to use a place you are going to as the observer. On an observation deck, don’t forget to enter the floor height. In the Bunkyo Civic Center example, the sun sits on the summit of Mt. Fuji at about 16:25 on November 9 and about 16:55 on February 2.

Try it in the app

Note

This article was translated from the original Japanese.