NG Knight Lamune & 40 1990

Baba Lamune, a 4th grader, is pulled into another world after he beats a video game he bought from a street peddler. He arrives in Hara-Hara to discover he's destined to save the world from the evil Don Harumage, with the help of the Guardian Knights, free-thinking robots. The writing is heavy with word-play; even the characters are named after popular Japanese drinks. It has 4 sequels, including 3 OVA, named "[NG or VS] Knight Lamune & 40"