Japanese Sign Language, abbreviated as JSL in English, is called nihon shuwa (Japanese finger-talk) in Japan. Like most sign languages around the world, it is very different from any other sign language; in particular, Japan's use of hiragana and katakana syllabaries make fingerspelling in Japanese difficult to master for those who have come from an alphabet-based system such as American Sign Language or British Sign Language.
JSL uses handshapes common to other sign languages, as well as handshapes not seen elsewhere. Some handshapes that are present in JSL but not ASL, for example, are middle-finger extended (a rude gesture in the United States), fingers 1-2-3 forming an O with fingers 4-5 extended, and so forth. Conversely, ASL has handshapes, such as the open 8, that are not present in JSL.
JSL has been formalized over the years through the work of the Japan Federation of the Deaf (JFD). Karen Nakamura is a prominent English-language author regarding JSL and Japanese deaf culture.