To get the secret Honorary Bro! Achievement/trophy you must complete the Bros Quest which is found in World 2 on the mansion's 2nd floor. To begin this side quest must go up the left stairs at the Manor and keep going left in the foyer. If you look behind the two spiders that are in this hallway you will see a doorway you will meet a ghost called Bono who will give you a quest that that requires tracking down his 5 brothers and bringing them all an item that they need to attend a party.
There are 5 items and 5 ghosts you must talk to twice, the first time in order to get a hint as to where their items are, and the second time for them to go back to their brother. The locations of each brother and their corresponding item is as follows:Breis
On the table in the room with Brono.
- Where to find Breis
You will find Breis in the Dining Room, which is directly to the left of the Kitchen. The party hat is also in the kitchen.Brodos
Found in Storage Room where the quest begins (B-2). You can access the Storage Room by going through the first door you come across and then going left until you find them.
- Where to find Brodos
You will find Brodos in the room right next to the room with Brono.Brinco
In the First Floor Rooms. These are the rooms in which you met Handy and Bella. The perfume can be found in the middle room.
- Where to find Brinco
You will find Binco in the lavatory, which is found in the top-left doorway of the mansion foyer. It is the first doorway in this hallway.Bres
In the Library, which is on the third floor. To get there, go outside through the broken window, climb up to the highest entrance outside, then enter the left doorway in this hallway.
- Where to find Bres
You will find Bres in Storage Room B-3, which is directly to the right of B-2, where the balloons are.Brato
- Party Hat
The party hat can be found on the second floor in the Kitchen. To get there you need to go outside through the broken window and enter the entrance that is to the left of where you came out.
- Where to find Brato
You will find Brato in the Ballroom, which is the top-right entrance in the foyer. You will need to climb to the top of the room to find him.
Once you have found all the items and gave them to the ghosts, talk to the first ghost to get the Achievement/Trophy as well as the Key to the Dark Maze.