The Legend of Zelda: Majora's Mask/Join the Bombers Gang

Requirements

 * Human Link (for the notebook)

Rewards

 * Bombers Gang Password
 * Bombers' Notebook

What to Do
Begin by playing the Hide and Seek game with the Bombers Gang, by first popping the balloon in North Clock Town. Find their locations (See Prologue for more info). When you find all the Bombers as Deku Link or as a non-human, they won't accept you into the gang, but they will treat you as an honorary member and give you their password required to access the observatory. However, if you are in Human form, they will give you their password and the Bombers Notebook, which contains the password, the time, and records of the troubled lives of people that you've helped.

While the password changed from game to game, it remains constant for that saved game.

An alternate method is to use the password you learned in the Prologue to get into the Bomber's Hideout as Human Link. When you leave, you will be given the Bomber's Notebook.