Villagers have the option of undergoing surgery to increase their health. The cost in ryo for your surgery is approximately 12% of your current maximum HP. After performing the surgery, you enter a recovery period of three hours. Until then, you may not perform missions, or use the battle arena.

Because of this, it is advisable that you complete a mission before paying for a surgery, to maximize your HP gain per three hours. After the three hour recovery period is up, you will receive your HP gain upon waking up. It is also advisable to refrain from buying surgeries until at least Chuunin, as the Genin/Student gains are abysmal for the three-hour wait.

For Chuunins+, the gains mirror those from each rank's respective highest mission.

• Surgery Calculator
• Regarding Genin Surgeries