More Japanese firms hit by large-scale data breaches

According to The Japan Times, JR East said that about 6.09 million customer accounts may have been compromised, while JR Kyushu said about 1.3 million customer accounts may have been compromised. Both were a result of a ransomware attack on IDC Frontier, a cloud services subsidiary of SoftBank, they said Friday.[2]The Japan Times reports that Bookoff Group Holdings, a secondhand goods retailer, reported that its subsidiary responsible for managing membership data had suffered unauthorized access, possibly resulting in a data breach affecting up to 6.43 million customers.[2]The paper also reports that Daiichikosho, the operator of the Big Echo karaoke chain, said personal information on about 8.72 million customers may have been compromised due to unauthorized access to a system managed by an external contractor.[2]The Japan Times says Adventure Inc., the operator of the Skyticket travel booking website, reported a potential breach involving about 14.64 million sets of personal in[2]formation.Jiji Press reports that the information leaked at Bookoff and Daiichikosho includes names, date of birth, email addresses and phone numbers[3]. According to Jiji, the two firms said misuse has not been confirmed[3], but they warned customers about possible fraud emails and phone calls.Earlier in the week, The Japan Times quoted Chief Cabinet Secretary Minoru Kihara as saying "it is not clear whether these incidents are related"[4].Tech Insider, citing security firm Trend Micro, reports that Japan's 600 publicly disclosed incidents through September already beats the 593 cases logged across the entirety of 2025[5].