Deleting data, sending snarky emails... The reality of "revenge resignation" that troubles workplaces

In recent years, "revenge resignation"—a resignation accompanied by retaliation against the company or superiors—has become visible in Japan. Common methods include: ① mass deletion of work data from shared servers or SaaS platforms, ② sending mass emails or posting on social media with complaints or slander against the company internally and externally, and ③ sudden resignation or abandonment of duties during busy periods. For example, in January 2025, a former employee's automatic deletion of 232 folders was recognized in court as grounds for damages (approximately 5.77 million yen), clarifying the tangible harm. On the criminal side, there is the potential for charges under the crime of obstruction of business by damaging a computer (Article 234-2 of the Penal Code), and on the civil side, there is the possibility of claims for damages based on tort or breach of contract. If personal information is involved, there may also be obligations under the Personal Information Protection Law to report and notify the individual. For companies, countermeasures include standardizing offboarding processes, immediate revocation of access rights, unchangeable backups, log preservation and forensic collaboration, improving work regulations and NDAs, and creating a psychologically safe workplace. Employees are encouraged to use public consultation services or internal systems appropriately instead of engaging in illegal retaliation. Below, we will provide a detailed explanation of the latest trends in case law, legal risks, and practical countermeasures.