Montedio Yamagata is based in the northern town of Yamagata, about halfway between Tokyo and the northernmost tip of the main island. The team was formed in 1984, as the club team of NEC's Yamagata factory. In a relatively rural area, the team was one of the strongest and best supported, winning the regional league four times between 1984 and 1992, when the J.League was created and the rest of Japan's domestic football structure was reorganised. In 1994, after winning a regional title in the new Tohoku Regional League, the team advanced to the JFL.
In 1998, prior to the formation of the J.League second division, NEC granted the football club its independence, and the team changed its name to Montedio Yamagata. The team takes its name from the Italian words monte and dios, which literally means the "Mountain Gods", or perhaps more accurately from a Japanese perspective, the "Mountain Kings". This is a very appropriate name, as Yamagata is a rugged, mountainous prefecture in northern Japan, known for a harsh climate, brave and rugged men, and famously beautiful women. Montedio was a founding member of the J2, and a very healthy and energetic fan base has allowed the team to battle into the J1 on several occasions in the past. The mascots are Monte -- who represents the mountains surrounding the city, and Deo, who is supposed to be a Japanese serow (mountain goat), but sports an extra horn in the forehead, making him look a bit like a unicorn.