Jinko (agarwood) (沈香)
Jinko (agarwood), formally known as Jinsui Koboku (sinking fragrant wood), is one of the most popular types of koboku (fragrant wood). When the bark of Aquilaria trees in the family Thymelaeaceae (Latin name: Aquilaria agallocha), native to southeast Asia, is damaged by wind and rain, disease, pests, etc., they secrete a resin inside the damaged area to protect the heartwood. Jinko can be obtained by removing the damaged area after the accumulated resins are dried. Prior to the damage, the heartwood is very light with a density of 0.4, which becomes higher as the resin is accumulated to make the heartwood sink in water.
The name 'Jinsui' (sinking in water) comes from this phenomenon
Trees' trunks, flowers, leaves do not scent, but they exude a distinctive fragrance when heated. Thanks to nuanced variance in the scent of Jinko even though harvested from the same tree, it is suitable for use in Kumiko (combination incense) practiced in Kodo, a Japanese traditional ceremony where participants smell the slight difference in the aroma of incense. Jinko is classified into several categories according to the type of fragrance, production area, etc. Jinko of the most excellent quality is called 'Kyara' (agalloch) and appreciated. It is said that the origin of the word Kyara is the Sanskrit word 'Kaaraaguru,' which means black, and Kyara is also referred to as Kyananko, or Kananko. A detailed description of Jinko classification is provided by articles about Rikkoku-gomi (the six countries where Jinko is from and the five elements used to describe their aromas). Siam Jinko refers to Jinko produced in Indochina, which has a distinctive sweet aroma. Tani Jinko refers to Jinko produced in Indochina, which is characterized by an aroma accentuated with bitterness. Jinko is also a herbal drug with a tonic and sedative effect and is used as an ingredient for herbal medicine such as Hiya Kiogan. The word 'aloes' was used to describe agarwood in old English, which led to the misunderstanding that aloe (aloe vera) was one of the fragrant woods. Needless to say that agarwood and aloe belong to completely different families.
The most ancient description of Jinko is that a fragrant wood washed ashore on a beach on Awaji Island in May to June 595, and this is said to be the first introduction of Jinko to Japan. According to a folklore introduced in the Nihonshoki (Chronicles of Japan), (Awaji) locals, finding that the wood that washed ashore exuded a pleasant smell when putting it on a fire, presented the wood to the Imperial Court as a tribute, and the wood was appreciated by the Court. The huge Jinko named 'Ojukuko,' which is 156 cm in length and 43 cm in the maximum diameter and weighs 11.6 kilograms, is housed in the Shoso-in Treasure Repository at Todai-ji Temple together with other treasures. It is considered that this bulky Jinko was brought to Japan prior to the Kamakura period, and thereafter, powerful leaders of the time cut pieces from the bulk. The places in Ojukuko from which the eighth Shogun of the Muromachi bakufu (Japanese feudal government headed by a shogun) Yoshimasa ASIKAGA, Nobunaga ODA, and the Meiji Emperor cut pieces are tagged. A record housed in Todai-ji Temple reads that Nobunaga cut two pieces of Jinko from the bulk that were 3.03 cms by 4 cms. In April 1992, the National Association of Takimono Senko Unions designated the 18th of April as 'Incense Day' because April was the time when, as identified by the above-mentioned descriptions in the Nihonshoki, Jinsui Koboku had arrived Japan for the first time, and the word '香' ('incense' in English) can be associated with the 18th, as the word can be divided into '十' (ten) and '八' (eight), thus equaling 18.