Bon | biwa | cajon | chaos pad | daiko | fue | gagaku | hichiriki | kabuki | Kaoss Pad | kokyu | koto | manga | narimono | nokan | O-Bon | pipa | ryuteki | sanshin | sanxian | shakuhachi | shamisen | sheng | shinobue | sho | sitar | suona | tabla | taiko | tonkori | Tsugaru-shamisen | yueqin

Some general sources:

Japanese traditional music produced by Columbia Music Entertainment: here

The Musical Instruments E-book, from Hong Kong: here

Biwa - a Japanese short-necked fretted lute, corresponding to the Chinese pipa and the middle-eastern ud, associated with music, eloquence, poetry, and education in Japanese Buddhism. The playing of the biwa nearly became extinct during one period as Western music and instruments became popular, but is now cultivated again. There are six types of biwa, chacterized by number of strings, sounds it can produce, type of plectrum, and their use. More here.
Bon, Obon - a Japanese Buddhist holiday to honor the departed spirits of one's ancestors, traditionally including a dance festival, held from 13-15 July. Nowadays a family reunion holiday during which people from the big cities return to their home towns and visit and clean their ancestors' graves, and held in August to coincide with the summer holiday period. More here.
cajon, cajón - literally a 'big box' in Spanish, originally a box played as a drum with the hands, now specially made for the purpose: it has its origins in Afro/Latin-American music. More here.
chaos pad - see Kaoss Pad
daiko - see taiko
dizi - a Chinese transverse flute, known under many different names, spellings and transliterations, which is widely used in many genres of Chinese folk music, opera, and the modern Chinese orchestra. Traditionally, the dizi has also been popular among the Chinese common people, and it is simple to make and easy to carry. The dizi has an extra hole between the embouchure and finger-holes, a taut membrane is glued over the hole to create a penetrating buzzing, nasal quality. Dizi are often played using various "advanced" techniques, such as circular breathing, slides, popped notes, harmonics, "flying finger" trills, multiphonics, flutter-tonguing, and double-tonguing. Professional players usually have a set of seven dizi, of different sizes and each in a different key. More here.
fue - a Japanese bamboo flute with seven holes: more here and here.
gagaku - literally "elegant music", a form of Japanese classical music that has been performed at the Imperial court for several centuries. By this time, the present ensemble style which consists of three wind instruments, hichiriki, ryuteki, sho, and three percussion instruments, kakko, shoko , taiko. A number of western composers have embraced the style, including Olivier Messiaen and Benjamin Britten. More here.
hichiriki - the most widely used of all instruments in Japanese gagaku, with a double reed like the oboe, a cylindrical bore like a clarinet and a sound that many describe as "haunting"; pitch and ornamentation are controlled largely with the embouchure. More here.
kabuki - a form of public entertainment cahracterised by being eccentric or extraordinary or outside the bounds of common sense. The distinctive feature of Kabuki expression is that it does not tend toward realism like that of modern plays. Kabuki has developed in the direction of stylized performances, persistently pursuing on-stage expression that goes beyond mere realism. More here.
Kaoss Pad, chaos pad - a touchpad MIDI controller, sampler, and effects-processor for audio and musical instruments, made by Korg. The touchpad is used to control effects include pitch shifting, distortion, filtering, wah-wah, tremolo, flanging, delay, reverberation, auto-panning, gating, phasing, and ring modulation. The most recent model can process both sound and video. More here.
kokyu - the only traditional Japanese bowed-string instrument, looking like a small shamisen and is played upright, with the horsetail-strung bow rubbing against the strings. Traditionally having with three strings, a four-stringed version has expanded the instrument's range and popularity. It has also been used in jazz and blues. In Japanese the term may refer broadly to any bowed string instrument of Asian origin. More here.
koto - a traditional Japanese stringed instrument, about 180 cm long and with 13 strings that are strung over movable bridges along the length of the instrument. Players can adjust the string pitches by moving these bridges before playing, and pluck the strings with finger picks on the thumb, forefinger and middle finger.There is also a version with 17 strings. More here.
manga - in Japan, the normal word for comics and print cartoons, literally "random or whimsical images": outside of Japan, it refers to comics originally published in Japan. Popular manga are often adapted into anime, Japanese for 'animation' once a market interest has been established. Animanga are anime printed in manga style. Themes include sports, romance, historical drama, comedy, soap operas, fantasy, mystery and horror. More here.
narimono - percussion instruments: the word is also used in various other senses
nohkan, nokan - the bamboo flute used in the noh drama and kabuki theatre. Constructed so that the intervals between notes are uneven: the pitches produced are not standard, each instrument is different. It features an extra, short, internal tube, to produce very sharp notes. More here.
Obon, O-bon - see Bon
pipa - a plucked Chinese lute, related to the Japanese biwa, originally having twisted silk strings and played with large plectrum, nowadays with nylon-wound steel strings played with false nails or finger picks of plastic or tortoise-shell. More here.
ryuteki - a Japanese bamboo flute used in gagaku, one of the three used in particular to play songs of Chinese style, with seven holes, 40 cm long: literally "dragon flute", the sound is said to represent the dragons which ascend the skies between the heavenly lights, represented by the sho and the people of the earth, represented by the hichiriki. The holes are covered by the the fleshy part of the finger rather than the tips, which allows for better control of "half-holing" techniques and chromatic notes, by simply raising the finger slightly above the holes. More here and here.
sanshin, sanxian - literally meaning "three strings", a fretless long-necked lute, in Japanese/Okinawan sanshin, in Chinese sanxian, in Japan the precursor of the larger shamisen; something like a banjo, with its resonating table of stretched snakeskin; played with a plectrum on the index finger, a guitar pick or the nail of the index finger. In the late 20th century a four-stringed version was also developed, and it is used in many different kinds of folk and classical ensembles. More here and here.
shakuhachi - a Japanese end-blown flute which is held vertically, traditionally made of bamboo, now also wood and plastic. It was used by Zen Buddhist monks in the practice of meditation. Popular in Western 1980s pop music. More here.
shamisen, samisen - a fretless long-necked Japanese three-string lute, evolved from the sanshin, played with a large plectrum of ivory, tortoise-shell or wood, or plucked with the fingers; resonating table made ofdog or cat skin, paper or plastic. The plectrum can be used to strike both string and skin, creating a percussive sound. Tsugaru-jamisen is a genre of shamisen music from Tsugaru, at the northern end of Honshu island, traditionally one of the poorest and remotest areas of Japan; performed throughout Japan nowadays, the style is characterised by its lilting rhythm and percussive quality, since the plectrum strikes the body of the instrument on each stroke. It uses a larger shamisen with thicker strings and a smaller plectrum. Tsugaru-jamisen playing styles are now combined with jazz, rock and other forms. More here and here; photo with permission from here.
sheng - a mouth-blown free reed instrument with 17-36 vertical pipes, giving a warm mellow sound; traditionally, the holes on the pipes are opened and closed pressed directly by the player's fingers, since the 1950s also by keys or levers; traditionally used for accompaniment to solo suona and in small ensembles, nowadays used for both melody and chordal accompaniment. The Japanese sho was modelled on it, but developed independantly from it; in the early 1800s the sheng inspired the invention of the Western harmonica, accordion, and reed organ. More here.
shinobue - a Japanese transverse flute with a high-pitched sound, playing important roles in noh and kabuki theatre musicstyles: Uta(song), and Hayashi(festival). More here and here.
sho - a mouth-blown free reed instrument with 17 vertical pipes, giving a warm mellow sound; the holes on the pipes are opened and closed pressed directly by the player's fingers; modeled on the Chinese sheng, the sho has developed independently in Japanese culture and became one of the three primary woodwind instruments used in gagaku, the imperial court music. More here.
sitar - an Indian long-necked lute with 6 or 7 are playable strings, running over curved, movable frets, 11-14 sympathetic strings running underneath the frets and with a gourd as a resonating chamber. Three of the strings provide the drone and the rest are used to play the melody, though most of the notes of the melody are played on the first string. More here.
suona - a loud and high-pitched Chinese shawm or oboe used in traditional music ensembles, particularly outdoors, for festival and military purposes; an important instrument in the folk music of northern China. It has also been used in Cuban folk music and by some jazz saxophone players. More here.
tabla - a pair of Indian hand drums of contrasting sizes and timbres, made of metal, wood or clay. The smaller drum is played with the dominant hand and tuned to a specific note, the larger drum, played with the other hand, has a much deeper tone. Fingers and palms create a wide variety of different sounds, the heel of the hand is also used to apply pressure to change the pitch. Traditionally there were half-a-dozen distinct playing and composing styles, secrets which were closely guarded and often only passed along family lines, but today both the distinctions and the secrecy are disappearing. More here.
taiko - means simply "drum" in Japanese, but outside Japan it refers to a special art-form of ensemble drumming used in both folk and classical musical traditions such as noh and kabuki. They have heads on both sides, and a sealed resonating cavity; tuned in high tension, though not usually to specific notes. The tensioning system is usually rope. They may be set on a stand or be strapped to the body so the drummer can move and play at the same time. Some of the drums are so large that they cannot even be moved so they’ve taken up residence inside a temple or shrine. 'Daiko' is a form used when 'taiko' is written together with other words. More here.
tonkori - a plucked zither played by the Ainu people of northern Japan and Sakhalin, similar to the various kanteles of northern Europe, with a body of spruce and three to five open strings of gut or vegetable fibre. More here.
Tsugaru-shamisen, Tsugaru-jamisen - see shamisen.
yueqin, yue qin - a Chinese short-necked lute with a round body, also called moon guitar, moon-zither, etc.; like a modern mandolin it has four double-courses (pairs of strings) tuned in fifths: an important instrument in the Beijing opera orchestra, often taking the role of main melodic instrument. More here.