In ball games, it is important that the players are able to estimate the position of the other players from a bird's-eye view based on the information obtained from their first-person view. We have developed a training system for improving this ability. The user wears a head-mounted display and can simulate ball games in 360° from the first-person view. The system allows the user to rearrange all players, and a ball from the bird's-eye view. The user can then track the other players from the first-person viewpoint and perform actions specific to the ball game such as passing, receiving a ball, and (if a defense player) following offense players.