The official web site of Japanese Association for the Study of Extracurricular Activities (JASEA) is: https://jasea.net/
This website ( tokkatsu.jp ) is operated by the International Exchange Committee, of JASEA, that promotes and disseminates Japanese Tokkatsu (Special Activities) practices and research to an international audience.
Tokubetsu Katsudou (composed of Class Activities, Student-Coucil Activities, Club Activities, and School Events) is deeply embedded in official school curriculum as described in the Course of Study by the MEXT of Japan.
Its official translation by the MEXT is now "Special Activities".
The MEXT is considering a new translation: Tokkatsu (Student-Led Activities for Civic and Personal Development)(1).
Tokkatsu is an abbreviation of Tokubetsu Katsudou in Japanese.
Japanese Association for the Study of "Tokubetsu Katsudou" is now using a translation "Extracurricular Activities" for "Tokubetsu Katsudou" but it is important to note that "Tokubetsu Katsudou" is NOT 'extra' at all but a significant part of school curriculum in Japan.
NOTE (1)　The Ministry of Education, Culture, Sports, Science and Technology (MEXT) Curriculum Committee's Special Activities Working Group (Nov 17, 2025), handout 1 focusing on restructuring special activities, slide 5, https://www.mext.go.jp/b_menu/shingi/chukyo/chukyo3/115/siryo/mext_00003.html?__CAMVID=cFQFChihGIcd&_c_d=1&uns_flg=1&__urlmid=11620660&__CAMSID=gUgfChiHGICD-88&__CAMCID=hzgulsiKBZ-018&adtype=mail , retrieved November 23, 2025.