G.I.S.M. (ギズム Gizumu) was a Japanese hardcore punk[1] / heavy metal band formed in Tokyo in 1981. Even though the guitar style resembled heavy metal in many aspects, GISM was one of the first Japanese hardcore bands, while at the same time drawing influence from the early industrial/avant-garde music scene—something uncommon in punk bands at that time.

The acronym GISM has many different variations; they include: "Guerrilla Incendiary Sabotage Mutineer" (original), "God In the Schizoid Mind", "Grand Imperialism Social Murder" and "Gnostic Idiosyncrasy Sonic Militant".

GISM has attained a cult status in the international punk scene, duly for their unique blend of heavy metal and hardcore punk. Roadrunner Records ranked Sakevi Yokoyama No. 49 out of 50 of The Greatest Metal Frontmen of All Time. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.