There is no way around the 13 heart restriction to get the Master Sword; unless you hack the game that is. If you wish to gain the Master Sword, you have two options:

• Locate 4 more shrines and gain 1 heart. If you use the Sheikah Slate or online guide, locating these shrines will be easy
• Complete the The Statue's Bargain quest. Completing this quest will allow you to exchange stamina bars for hearts and vice versa

Based on this guide, those who have the Master Sword during 3-heart challenge runs take advantage of the The Statue's Bargain quest. They will do shrines until they reach enough stamina that is equivalent to 13 hearts. They will temporarily exchange their stamina for 13 hearts, get the Master Sword, and then go back to 3 hearts

There is no way around the 13 heart restriction to get the Master Sword; unless you hack the game that is. If you wish to gain the Master Sword, you have two options:

• Locate 4 more shrines and gain 1 heart. If you use the Sheikah Slate or online guide, locating these shrines will be easy
• Complete the The Statue's Bargain quest. Completing this quest will allow you to exchange stamina bars for hearts and vice versa

Based on this guide, those who have the Master Sword during 3-heart challenge runs take advantage of the The Statue's Bargain quest. They will do shrines until they reach enough stamina that is equivalent to 10 hearts. They will temporarily exchange their stamina for hearts, get the Master Sword, and then go back to 3 hearts