Hokudai is what people call Hokkaido University. The University is in Sapporo, Japan (where that beer comes from), which is on the northern island of Hokkaido. Hokkaido is Japan's Wild North.
Ōendan are Japanese cheerleaders, the word translates to something like "cheer group." Ouendan are different from American cheerleaders in that they are usually mostly men. They normally dress real sharp: with their buttons and armbands you'd think they were Soviets.
So what do you get when you mix wild North with male cheerleader? A homeless-looking guy waving a dirty flag? Way. I'm not sure how or why, so I made up this story to explain it: You are a swimmer, or a lacrosse player, or rugby or running or whatever---there is a lot to do---you have been practicing but you are pretty invisible and don't expect much turn out. How would you feel knowing that three country boys had traveled three days on foot to see you play. They have no money or teeth, but they know your name, and the names of all your teammates. They are completely psyched---for you---and they are waving a big dirty flag tied together from strips of cloth and banging a big drum with bad rhythm.
Hokkaido University's cheer squad also has the normal kind of ouendan, like with buttons and armbands. What I've been told is that first- and second-year men have to be dirty, so they get hairy and don traditional rag-robes and platforms. Upperclassmen go clean-cut. Most of the squad lives at the school's traditional self-governed dorm, where students do other traditional things like sumo and writing songs to honor things.