Short answers, pulled from the story.
Emakimono is Japan's tradition of illustrated horizontal handscrolls that combine calligraphy and painted scenes, dating back to the Nara period between 710 and 794 CE. The scrolls were painted, drawn or stamped on long rolls of paper or silk and read by unrolling them by hand.
The earliest surviving Japanese emakimono dates to the 8th century, during the Nara period, and depicts the life of Gautama Buddha up to his Illumination. Handscrolls themselves originated in China and reached Japan through the spread of Buddhism. This early work is very likely a copy of an older Chinese model.
The Four Great Illustrated Handscrolls of Japan are also known as the Nihon Yondai Emaki. They are the Ban Dainagon Ekotoba, the Chōjū-jinbutsu-giga, the Genji Monogatari Emaki and the Shigisan Engi Emaki. All four date from the late Heian period and have been designated National Treasures of Japan.
Art historians describe the 12th and 13th centuries as the golden age of emakimono. This span covers the end of the Heian period and most of the Kamakura period. Production became more sustained under the new warrior class and new Buddhist sects, and painters merged the onna-e and otoko-e styles with sharper realism.
An emakimono was read by a single person sitting on a mat, with the scroll placed on a low table or the floor. The reader unwound it with one hand while rewinding it with the other, moving right to left. About 60 centimetres of the story was visible at a time.
Around 20 emakimono are protected as National Treasures of Japan today. Few scrolls have survived intact, making this group a small remainder of a much larger historical output.