How Ninja Used Cats to Tell the Time

PUBLISHED 8 JUNE 2026

The Resourceful Art of Telling Time in Feudal Japan

In an age before wristwatches, smartphones, and even widespread mechanical clocks, knowing the time could be a challenge. For the ninja, however, accurate timekeeping was often essential when carrying out missions, coordinating movements, or gathering intelligence. As a result, shinobi developed a variety of ingenious methods to estimate the time of day.

One common approach was to observe nature. During daylight hours, the position of the sun provided a rough indication of the time. At night, the stars could be used, with the Big Dipper serving as a useful celestial guide.

Yet the ninja had an even more unusual method at their disposal: using the eyes of a cat.

According to traditional ninjutsu teachings, a shinobi could estimate the time by carefully observing a cat's pupils. A cat's eyes respond to changing light levels throughout the day, with the pupils dilating in low light and contracting in brighter conditions. By studying the shape and size of the pupils, an experienced operative could make an educated guess about the time.

The technique required practice and observation. A ninja would need to understand how a cat's eyes typically changed over the course of a day and compare what he saw with his accumulated experience.

Of course, the method was far from perfect. Weather conditions, shade, seasonal variations, and location could all affect the amount of light reaching the cat's eyes, making precise timekeeping difficult. Nevertheless, it demonstrates the resourcefulness for which the ninja became famous.

While a cat may not replace a modern watch, the technique offers a fascinating glimpse into the practical ingenuity of the shinobi. When conventional tools were unavailable, ninja learned to use the world around them—even a household cat—to gather the information they needed.