Drain Syndrome

Drain Syndrome is an ancient disease that Nanahoshi had, which

Description
It's a condition that occurs when a human with little or no magical power naturally accumulates magical power over time, until their body begins to react negatively to it. In other words it's a disease that results from having mana within body that is uncapable of holding mana. Because of this, they must regularly drink tea made from Sokasu Grass, which will alleviate them condition by releasing the accumulated Magical Power through their waste. However this does not cure their condition, as they must continue to drink the tea from Sokasu Grass.