Baiu was one of the genin from the Hidden Rain Village that participated in the chuunin exams. Alongside his teammates, Shigure and Midare, they were one of the two Rain teams that made it into the 2nd phase of the chuunin exam. The other Rain team consisted out of Kagari, Mubi and Oboro. Not much is known about Baiu and his team, except for the fact that they were easily defeated by Gaara.
Baiu and his team were very unfortunate to run into Gaara while in the Forest of Death. In order to get another team's scroll and advance to the next phase of the chuunin exam, Shigure confronts Gaara using his Raining Needles technique, but gets killed rather easily. After Baiu and Midare saw Shigure get defeated so easily, they both immediately surrender, and give up their scroll. But Gaara shows no mercy for Shigure's teammates, and also finishes them off by trapping them within the Desert Coffin, and crushing their bodies with the Desert graveyard technique. In the end it was only Shigure that tried to fight Gaara, while Baiu and Midare just gave up, and still got themselves killed.