Sendan-ko (N-112) and Byakudan-ko (N-113) are fragrant wood bars (both are sandalwood) and Jinsui-ko (aloeswood) (N-114) has a form of a twisting root. As many fragrant woods are produced in Tropical Asia, not only were they highly prized at that time as imported goods, but they are valuable still now as materials for incense and fragrances. According to the Chronicles of Japan (Nihon shoki), the beginning of the use of fragrant wood in Japan was in the era of the Emperor Suiko when a sunken tree was cast ashore on Awaji Island and was offered to the Imperial Court. Then along with the rampant Buddhism, a wide variety of fragrant woods were imported from mainland China to Japan and many such woods are preserved in Shosoin Imperial Repository as treasures now. According to the "Horyu-ji Garanengi-narabini-rukishizaicho" (the Composite Register of the History and Materials of the Horyu-ji Temple Complex), it is described that "Sixteen kinds of incense in total; four types of Kunriku-ko for statues of Buddha, 168 ryo of which was bought by the temple; Jinsui-ko 10 ryo, Sen-ko 385 ryo, Kunriku-ko 46 ryo and Seiboku-ko 48 ryo were delivered to the Empress in the Palace of Heijokyo on the twenty-second day of the second month of Tenpyo 8 in the older fire-mouse year and ten types for Buddha; i.e., Byakudan-ko 407 ryo, Jinsui-ko 86 ryo, Sen-ko 403 ryo 2 bu, Choji-ko 84 ryo, Ansoku- ko 70 ryo 2 bu, Kunriku-ko 511 ryo, Kansho-ko 96 ryo, Fu-ko 96 ryo, Sogo-ko 12 ryo and Seiboku-ko 281 ryo in addition to Byakudan-ko 496 ryo for saint priests and Byakudan-ko 160 ryo for pagodas were delivered to the person in charge of the Empress in the Palace of Heijokyo in the second month of Tenpyo 6 in the older tree-dog year." There are many kinds of incense seen there.
Fragrant wood was used as a tool for the Buddhist memorial services by burning it before the tablet of the deceased at that time and also used as materials for craft objects such as boxes, hilts and scabbards of swords, tubes into which Buddhist Scriptures were put for burying (Kyozutsu) and the shafts of writing brushes, considering the mothproof effect. Among the treasures in the Shosoin Imperial Repository, Jinsuikogano sugorokukyoku (a Japanese variety of backgammon made of aloeswood), Byakudan-hakkaku-bako (an octagonal box made of sandalwood), Jinko-no-tsukasaya-no-tosu (a knife with a hilt and scabbard made of aloeswood), Jinko-matsu-nuri- Kyozutsu (a Kyozutsu tube coated with aloeswood powder) and Mizoryo-jinko-mokugano-fudenokan (the uncompleted shaft of a writing brush with marquetry of aloeswood) can be found. Among the Imperial Bequest to Horyu-ji Temple, the use of fragrant wood can be seen in a box with marquetry, a sutra box with marquetry, the Kyozutsu tube for a Lotus Sutra in Minute Characters, a Gyokuso-bako box and a Tosu knife. It is said that fragrant wood that sinks in water is called Jinsui-ko and one that doesn't sink in water is called Sensui- ko.
On the Sendan-ko, the inscriptions in black ink stating "Tei-go-kin in Enryaku 20," "Kotei-nijuyon-kin on the third day of the second month of Teno 2" and "Cut off in April, Meiji 11 (1878)" and one branded obscure sentence can be seen. On the Byakudan-ko, the inscriptions in black ink stating "Koteiju-juni-kin-hachi-ryo, the fourth day of the third month of Aza 5," "Byakudan Enryaku 20 Tei-jusan-kin," "Tuzura-yon-kin kyu-ryo," "Cut off on April 9, Meiji 11 (1878)," "To (pagoda)" and "Tera (temple)" and one branded obscure sentence can also be seen. On the Jinsui-ko, the inscription in black ink stating "Cut off on April 9, Meiji 11 (1878)" can be seen as well.