El-Hazard

From Wikipedia: "The story focuses on four people from our world (High school students Makoto Mizuhara, Katsuhiko Jinnai and Nanami Jinnai, and History teacher Masamichi Fujisawa) who are mysteriously transported to the fantastical world of El-Hazard, which is threatened with a massive war between the human nations on one side and the insectoid Bugrom tribe on the other. ... El-Hazard is a "light" series -- while it has a fair amount of character development, the series focuses almost entirely on action/adventure and comedy." This story is a manga adaptation of an anime franchise.