|1931：||“Jitsuryoku-Zoshin-kai” established at Kashiwagi Yodobashi-cho, Toyotama-gun, Tokyo. Commenced educational services, mainly distance correspondence education. The founder, Yutaka Fujii, was a former English teacher born in 1898 in Shimonoseki City, Yamaguchi Pref.|
|1945：||Evacuated from Tokyo to escape the air raids, and settled in Nakaizu-cho, Tagata-gun, Shizuoka Pref.|
|1952：||Changed company name to “Zoshin-kai”, with the abbreviation “Z-kai”; resumed services.|
|1979：||Relocated to a newly-constructed headquarters building in Nagaizumi-cho, Sunto-gun, Shizuoka Pref.
Introduced computers to begin streamlining and to improve efficiency.
|1981：||Started distribution of textbooks at designated bookstores.|
|1982：||Launched distance correspondence courses for students studying for high school entrance examinations.|
|1985：||Converted to a joint-stock corporation.
Opened a cram school, “Shingaku Z-kai”, in Shibuya-ku, Tokyo.
|1986：||Launched model entrance examination service for junior high school students.
Opened offices in Tokyo and Osaka.
|1991：||Launched preparatory course for the entrance examination to the University of Tokyo.|
|1992：||Constructed Tokyo Building in Ebisu, Tokyo.
Published the first edition of “Sokudoku-Eitango 1, 2” (Vocabulary building).
|1994：||Opened Osaka Learning Center to launch preparatory course for the entrance examination to the University of Kyoto.|
|1995：||Opened Ochanomizu Learning Center to operate preparatory course for the entrance examination of the University of Tokyo.|
|1999：||Transferred cram school business in the Tokyo metropolitan area to Tokyo Zoshinkai Inc.
Published “Oxford Word Power Dictionary”.
Launched distance correspondence course for elementary school students.
|2000：||Transferred cram school business in the Kansai region to Tokyo Zoshinkai Inc.
Transferred publishing business to Z-kai Publishers Inc.
|2001：||Constructed Ochanomizu Building in Kanda-Sudacho, Tokyo.|
|2002：||Published “Word Power Fully Bilingual Dictionary”.
Launched Business Development Courses.
|2003：||Changed the name of Tokyo Zoshinkai Inc. to Z-kai Taimen Kyoiku Inc. (cram school).|
|2006：||Merged Zoshinkai Publishers Inc. (distance correspondence education service), “Z-kai Taimen Kyoiku” (cram school business) and Z-kai Publishers Inc., to form Z-kai Inc.|
|2007：||Launched video streaming courses.
Launched Gakken Classrooms / Z-kai Courses.
|2008：||Acquired a part of the university entrance examination business of Gakkyusha Co.,Ltd.
Entered a business and capital alliance with ICHISHIN CO., LTD.
Entered a business and capital alliance with With us Corporation
|2009：||Constructed Z-kai Bunkyo-cho Building in Mishima.
Entered a business and capital alliance with Eikoh Inc.
|2010：||Launched a distance correspondence course for 4/5 year-old preschool students.|
|2011：||Established Facultas Co.,Ltd.|
|2012：||Launched “Digital Z”, providing digital educational materials for pre-school and elementary students.|
|2013：||Established Z-kai CA Inc.|
|Jan. 2015：||Invested in igsZ., Ltd.
Established Z-kai Learning Technology Inc.
|Jun. 2015：||Opened Z-kai Individual Teaching Center in Futakotamagawa.|
|Jul. 2015：||Formed a long-term strategic partnership with Knewton, Inc. to develop adaptive learning products for students.|
|Aug. 2015：||Formed a business alliance with KDDI to provide educational services making use of the advantages of ICT.|
|Sep. 2015：||Formed a business alliance with Edmodo, Inc. to develop and provide SNS and learning platforms for schools.|
|Oct. 2015：||Established Z-kai Educe Inc.|
|Jan. 2016：||Agreed with Peason Japan K.K. to develop and provide a new digital English educational service.|
|Feb. 2016：||Formed a business alliance with RareJob Inc. to sell online English conversation products and to develop English language educational services.|