Seijo ni Uso wa Tsuujinai

Chloe, an apprentice priestess in a remote church, is a greedy girl who makes money on the side by gambling at cards at night, using her insight and memory as weapons. One day, Erald, a high-class paladin, visits Chloe and asks her to infiltrate the grand cathedral as a saintess candidate, in order to find the culprit who committed a murder there two years go...?

(Source: Monthly Shonen Magazine, translated)