Cobalt Hour(コバルト・アワー,Kobaruto Awaa), stylized as COBALT HOUR, is Yumi Arai's third studio album, released on June 20, 1975 by Toshiba EMI/Express (now part of EMI Music Japan). The album was also distributed by Alfa Records for a period of time. On April 26, 2000, the recording was digitally remastered for re-release on CD by Bernie Grundman. Internet sales of the album began March 10, 2005.
The album cover was illustrated by Pater Sato. Though Arai's nickname "Yuming" is written on the cover, it is clear that the "g" was added later.