Answer

In Jain tradition, a person who completes 100 days of Upwas has performed a very difficult and highly respected tapasya.

However, if you are asking the name of a specific person who has done 100 days Upwas, I can only provide that if it is clearly established and verified within Jain tradition.

Explanation

Upwas means fasting with spiritual discipline, usually with the intention of:

• reducing attachment to the body,
• controlling desires,
• purifying karma,
• strengthening self-control and devotion.

A 100-day Upwas is not ordinary fasting. It is considered a very intense form of bahya tapa — external austerity.

Takeaway

Many Jain sadhus, sadhvis, shravaks, and shravikas have performed great tapasya, but I should not name anyone unless the information is clearly verified.