In order to cross the bridge in the Water Town of Saria that leads to Death Mountain, Link will have to talk to Bagu since the River Man only lets townsfolk cross. In the town, Link can find a purple Bot sleeping in Bagu's house who tells him where its master is if Link wakes it up. When the young hero finds Bagu, he will give Link a note to show to the guard, which allows him to pass the bridge at any time.
Bagu also appears in the fourth issue of the Legend of Zelda comic published by Valiant Comics. In this issue, he comes from the Moruge Forest and stays at the North Castle for few days, pretending to befriend Link and Zelda, but in a sudden moment, he betrays them and steals the Triforce of Wisdom. Link manags to catch up with Bagu and confronts him. Bagu soon realizes that Link has brought his Power Glove with him, and that he would be no match against such a weapon. He surrenders as he tells his tale to Link: Ganon had kidnapped his two pet frogs, and was holding them ransom, and demanded the Triforce in return. Link reluctantly offers to give Bagu his Power Glove so he can stop Ganon. It is unknown what events occurred during his attack on Ganon, but Bagu eventually returns safely to the palace with both of his frogs.
It is likely that the name Bagu is a joke from the developers, since he is quest-related to the character Error. "Bagu" would be the Japanese transliteration of the word "bug". As such, "bug" and "error" refer to a computer's malfunctioning.