More than 13 million personal computers in Japan will be exposed to higher risk of virus and other attacks starting in mid-April, experts warn.

These computers are still running the Windows XP operating system, which Microsoft Corp. will stop supporting entirely on April 9.

An estimated 7.23 million Windows XP-based PCs are still in use by companies, accounting for 20 percent of all PCs in Japan. Migration to newer operating systems, such as Windows 8.1, has been slow, especially at small and midsize firms, because managers are either unaware of the problem or want to avoid the cost of updating.

Included in the corporate category, according to a survey by the Internal Affairs and Communications Ministry last October, are town, city and prefectural governments, which have around 2 million PCs in use, 722,166 of them on Windows XP. About 37 percent of them, or 266,231 machines, won’t be upgraded by the April deadline.

Local governments have been slow to update old machines because much of their administrative work, including the handling of residential and taxation data, depends on Windows XP software.

If a company or local government shifts to a newer OS, it must also ensure that its spreadsheets, calculating and other software will successfully make the transition, which takes several months.

Microsoft Japan Co. will conduct seminars to help smaller firms make the migration through early April, aided by more than 10 regional chambers of commerce and industry. It is also offering incentives, such as by deferring payment for new PCs until after April or paying the interest on installment plans.

The software behemoth’s sales agents are also stepping up preparations for terminating Windows XP. Hardware seller and system integrator Otsuka Corp., for example, has bulked up on new machines in expectation of a sharp increase in demand.

An estimated 5.97 million PCs owned by individuals, or 14 percent of all PCs in Japan, are running Windows XP, which was released in 2001. While PCs are losing ground to tablet computers, the end of support for XP will “create opportunities for digging up demand for PCs” among individuals, said an official at leading PC maker Fujitsu Ltd.

In fact, PC makers have already launched sales promotions including price cuts and higher trade-in prices to capitalize on last-minute demand before the Windows XP deadline and the first stage of the doubling of the consumption tax in April.

The end of Windows XP support will also reportedly leave nearly all of the world’s ATMs vulnerable, boding ill for Japan’s banks, which have lost ¥760 million to Internet hackers as of Oct. 15, 2013.