The Taisho Emperor actually ascended to the throne upon the death of his father in 1912. The enthronement ceremonies, though, were held in 1915.

This medal commemorates that event, and it was freely issued to people throughout the country who participated in the celebration ceremonies. However, it doesn't seem to be as common as the later Showa Emperor Enthronement Commemorative of 1928. The gold mum crest is an attached piece.

OBVERSE: Imperial banners with 'Banzai' written within each. Branches of cherry and orange blossoms.
REVERSE: Inscribed 'Taisho 4 [1915] November, Enthronement 

Commemorative Medal.'

Peterson writes that the ribbon was 'designed from the drapes of the outdoor pavilion used in the ceremonies.'

This medal was also issued in a women's version (see below).