Seijo ni Uso wa Tsuujinai

Chloe appears to be a quiet, innocent novice training to become a priestess at a quiet countryside church. By night, however, she disguises herself and plays cards to win large sums of money. Her secret eventually becomes known, and a young holy knight named Heraldo arrives, seeking her assistance. He believes her magical ability can help solve a murder case from two years ago that is destabilizing the kingdom. Unbeknownst to Heraldo, Chloe's success at cards comes from her keen observation and clever mind, not magic. She must now rely on these skills to navigate the dangerous environment of the royal palace.