According to a press release, Japan’s Acquisition, Technology & Logistics Agency has revealed that they are indeed developing a new electromagnetic railgun.
On 31 July, Acquisition, Technology & Logistics Agency has released video footage showing a prototype of electromagnetic railgun for the first time. This is the first official confirmation of the development of a program a new generation of weapons systems for Japan Self-Defense Forces.
Details of the Japanese railgun programme have not yet been made available. It is noted that this electromagnetic railgun weapons system may be outfitted aboard on next-generation destroyers, possibly the Type 27DD.
The railgun utilizes a combination of electric and magnetic force to fire a projectile by means of a sliding armature that is accelerated along a pair of conductive rails. The railgun uses a pair of parallel conductors, or rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail.
The electromagnetic railgun is capable of firing a projectile 100 miles away and has a low cost of projectiles compared to conventional weaponry.
On top of the reduction in costs per projectile, the railgun limits the need to maintain a large quantity of heavy explosive tipped shells, increasing safety on board navy vessels, and reducing logistics costs and needs. Ships at sea can afford to stay out for longer periods without resupply, reducing the burden of at sea replenishment operations.
https://youtu.be/mPUSGd8gARg?t=8m15s