TOKYO -- The Japanese government will ask companies that prohibit their employees from taking a second job to explain their reasons, starting in July, Nikkei has learned, in a move aimed at encouraging more large companies to allow their employees to hold such jobs.

The rule is not mandatory, and companies that decline to provide reasons will not face a penalty. However, the government hopes to work with Keidanren, Japan's powerful business lobby, to urge more large companies, which have traditionally been cautious about allowing their employees to have a second job, to respond favorably to the request.

The government hopes that such disclosure will help job seekers find companies that are more open about side work. It also hopes this will foster greater diversity in Japan's work practices and encourage talent to move into growth areas.

The current government guidelines urge companies to allow their employees to take second jobs, in principle. However, many employers remain cautious, fearing that letting workers engage in side gigs will lead to poor performance, or that their skills and credibility might be used for moonlighting more than in their main jobs.

The guidelines also say companies can ban second jobs if they put an employee's safety or company secrets?? at risk, or for other reasons. The government will amend the guidelines and ask companies to disclose their stance on side jobs, and, in cases where they ban such work, their reasons for doing so.