Matsuwa (153.272E 48.05N) is an island in the Kuriles midway along the chain. It had a small air and naval base.
The island was bombarded by a cruiser-destroyer group on 13 June 1944. The timing suggests that this was intended as a diversion from the American landings at Saipan on 14 June.
References
The Pacific War Online Encyclopedia (c) 2007-2008 by Kent G. Budge. Index