I don't know all that much except that they had more than one system of telling the time at night, such as the watches of the night. The animals clock was based on the Chinese one but e.g. noon was the middle of the hour of the horse and not the beginning. Japan didn't abandon this style of clocks until fairly recently.
Here is an existing android app: https://github.com/aragaer/jtt_android
Here is a resource about Japanese clocks: https://wadokei.org
I don't know all that much except that they had more than one system of telling the time at night, such as the watches of the night. The animals clock was based on the Chinese one but e.g. noon was the middle of the hour of the horse and not the beginning. Japan didn't abandon this style of clocks until fairly recently.
Here is an existing android app: https://github.com/aragaer/jtt_android
Here is a resource about Japanese clocks: https://wadokei.org