Questions about the KOURAKU app
For questions, bug reports, or feature requests, please email us at:
Q. Which devices are supported?
iPhone / iPad running iOS 15.0 or later, and Android 7.0 (API 24) or later.
Q. Is the app paid?
It's free. There are no in-app purchases (IAP), subscriptions, or paid unlocks. The only monetization is a banner ad (Pangle) at the bottom of the screen.
Q. Do you collect personal information?
There is no account registration, and we do not collect or store personal information. The App stores only your theme setting, your ad setting (whether ads may be personalized), and your stage-clear records on your device. The "GPS Positioning" mode is a calculated simulation and never accesses your device's location. The ad SDK (Pangle) may collect advertising identifiers and similar data. See our Privacy Policy and How We Handle Personal Data.
Q. How do I turn off personalized ads?
Tap "About this app" at the top right of the home screen, open "Ad settings", and choose "Don't allow". Ads will still appear, but they won't be tailored to your interests. On Android, the same choice is also shown on first launch. On iOS, you can also change it in Settings > Privacy & Security > Tracking on your iPhone / iPad.
Q. Does it work offline?
All features except ads work offline.
Q. How do I use it?
Each screen has a short guide at the top of its control panel showing what to move and what happens. The info button at the top right explains the principle.
Q. What's the difference between "Explore" and "Challenge"?
In "Explore" you move the sliders freely to see the principle at work. In "Challenge" the answer is hidden and you work through a task: measure, find your position, then check your answer. Each mode has 5 stages, for 30 stages across the 6 modes.
Q. How do I clear my Logbook?
Tap the clear button (trash-can icon) in the "Logbook" on the home screen and choose "Clear" to erase the records of all cleared stages. Records are stored only on your device.
Q. Which mode should I start with?
Each mode card shows a difficulty label (Beginner, Standard or Advanced), and the first mode you haven't finished is marked "Start here". Tap the start button in the "Logbook" on the home screen (for example, "Start with Celestial Latitude") to open that mode right away. The challenges are easier if you first try the mode in "Explore" to see how it works.
Q. Which languages are supported?
Nine languages: Japanese, English, Chinese (Simplified and Traditional), Spanish, Portuguese (Brazil), Korean, German, and French. The app follows your device's language setting.
Q. Can it be used in schools?
Yes, feel free to use it for education in schools, cram schools, or self-study.
Q. How accurate are the simulations?
They use textbook-level simplified models (celestial latitude, longitude and chronometer, dead reckoning, chart and compass, tides, GPS positioning). They are not for actual navigation, positioning, or safety decisions; please consult reliable literature and observational data.
When reporting a bug, including the following helps us resolve it quickly:
KOURAKU is an education app about knowing where you are, by stars and charts — letting you explore six modes interactively, visuals-first, and test yourself across 30 challenge stages: Celestial Latitude, Longitude & Chronometer, Dead Reckoning, Chart & Compass, Tides, and GPS Positioning, from classical celestial navigation through to modern GPS. As the navigation module of the "Raku" series, it connects to KAIRAKU.
Version: 1.0.0