ガンバレテニス部 is a free iPhone game developed by BAIBAI Inc. It offers a simple and addictive mini-game where players can test their tennis skills. The goal of the game is to keep the rally going for as long as possible by hitting the ball back whenever it enters the zone.

The game features easy controls, making it accessible for players of all ages. With various types of balls to encounter, players can challenge themselves to see how long they can keep the rally alive. The game is designed to be a fun and entertaining way to pass the time.

If you're looking for a free and easy-to-play tennis game, ガンバレテニス部 is a great choice. Download it now and see how long you can keep the rally going!

Please note that it's important to take breaks if you start feeling tired or strained while playing.