Naval Institute
海軍協会
page 2
Naval Institute badge with original case. This is the White Distinguished Merit Badge.
(Note that 'white' refers to the color of the suspension bar. There are also badges with
red and purple bars.)

Although oftentimes these badges were silver, this is a late-war aluminum badge.
Another example of the White  Merit Medal.

A large number of differences in the badges and the cases.
Naval Institute Red Medal of Merit.
Japanese Navy Institute Special Member Badge.
Late war; made of aluminum.
Japanese Navy Institute Full Member Badge.
Japanese Navy Institute Medal of Merit. Hallmarked sterling
silver.
Japanese Navy Institute Medal of Merit.
Late war; made of aluminum.