No one is quite sure how cats arrived in Japan. The most supported hypotheses are that they traveled down the silk road from Egypt to China and Korea, and eventually made the hop to Japan. Why they came across also is debated. They may have come as ratters guarding precious Buddhist sutras written on vellum, or as expensive gifts traded between emperors. They may have been both, at different times.
The first evidence that cats were definitely in Japan come from the diary of 17-year-old Emperor Uda on March 11, 889 CE:
On the 6th Day of the 2nd Month of the First Year of the Kampo era. Taking a moment of my free time, I wish to express my joy of the cat. It arrived by boat as a gift to the late Emperor, received from the hands of Minamoto no Kuwashi.
The color of the fur is peerless. None could find the words to describe it, although one said it was reminiscent of the deepest ink. It has an air about it, similar to Kanno. Its length is 5 sun, and its height is 6 sun. I affixed a bow about its neck, but it did not remain for long.
In rebellion, it narrows its eyes and extends its needles. It shows its back.
When it lies down, it curls in a circle like a coin. You cannot see its feet. It’s as if it were circular Bi disk. When it stands, its cry expresses profound loneliness, like a black dragon floating above the clouds.
By nature, it likes to stalk birds. It lowers its head and works its tail. It can extend its spine to raise its height by at least 2 sun. Its color allows it to disappear at night. I am convinced it is superior to all other cats.”