Golden Time is a franchise that started out as a light novel series.
The light novel is written by Yuyuko Takemiya and illustrated by Ēji Komatsu.
The manga adaptation is illustrated by Umechazuke and produced by ASCII Media Works. It ran in the Dengeki Daioh Magazine back in October 2011.
The anime adaptation is directed by Chiaki Kon, written by Fumihiko Shimo, and produced by J.C. Staff.