Shuuen no Cathédrale

A short story about a nun who has huge faith in her religion and loves the people. One day she is tested as people in her city is being killed. She wants power to stop this evil and prays while crying for this power. As we know it's when we show weakness that evil finds its way in our heart so a cute little devil appears to make a pact with her. The nun decides to make the pack and use this power of evil in the name of good.

(Source: jCafe24)