An integral part of Japanese sports games
Ouendan is an important part of the sports culture in Japan. When you go to Japanese baseball, soccer and other sports games, the Ouendan lead the cheers so that the supporters can follow them. Although most of them are at the front of the stadium (near the sport players), there are several others all around the supporter-section of the stadium, assisting the supporters in telling them what cheer they will be doing.
I have been to Japanese soccer and baseball games and the Ouendan has a large role in creating a lively and energetic atmosphere. Even when the team is losing, the Ouendan and supporters stay positive and encouraging. If not going as a huge fan (like me), you may be confused about the cheers. However, by the end, you will come out of the stadium singing the songs with your friends and family!