The grandfather bust is an entirely cosmetic object, and is freely available to you at the very start of the game. It can be found in the backroom of the shoppe next to the Daily Finance Scroll.
The bust consists of only the head, neck, and part of the chest, which belongs to the player character's grandfather. The grandfather is the person who used to run the shoppe before the player came along. At some point the player received ownership of the shoppe, which was left empty. Some supplies and tools were left in the backroom, along with the grandfather's bust.