It is Japan's third-biggest refiner by sales after JX Holdings and Idemitsu Kosan.

[2] Cosmo in Japan traces its corporate roots to Maruzen Petroleum (丸善石油株式会社), a company established in 1931, although the oil business operated by Maruzen was originally established by Zenzo Matsumura in Kobe in 1907.

A major fire occurred at the Cosmo refinery in Ichihara, as a result of the 2011 Tōhoku earthquake.

[3][4][5] It was extinguished after ten days, injuring six people and destroying storage tanks[6] The ultimate cause was traced to the collapse of supports for LPG Tank 364, which had been filled with water and undergoing hydrostatic testing at the time the earthquake struck.

The new company, named Gyxis Corporation, started effective operations on April 1, 2015.