The Koushi (郊祀) ceremony ("ritual of the outskirts") is described in chapter 6 of A Thousands Leagues of Wind.

It was the empress who calmed the heavens and the earth, who propitiated the gods. Of the rites and rituals, the most important was the Festival of the Winter Solstice. The empress's role during the winter festival was to travel to the southern district of the city and there make offerings to Heaven and pray for the protection of the kingdom. This ceremony was called the Koushi.

The roboku (路木) is the riboku located at the heart of the Imperial Palace. As with the thorn oak, new species of plants can essentially be bioengineered via the roboku. The process is also discussed at length in "Blue Orchid."

The Black Tortoise (玄武), explains Wikipedia,

is one of the Four Symbols of the Chinese constellations. It represents the north and the winter season, and thus can be called the Black Tortoise of the North. In Japan, it is one of the four guardian spirits that protect Kyoto and it is said that it protects the city on the north. The creature's name is identical to that of the Taoist god Xuanwu, who is sometimes (as in Journey to the West) portrayed in the company of a turtle and a snake.

Labels: 12 kingdoms, black moon, fantasy, japanese, translations