Moto Sister Reijou no Migawari Okisaki Kouho Seikatsu: Kamisama ni Burei na Hito wa Kono Watashi ga Yurushimasen

Abandoned by her parents at a young age, Elsie grew up in a convent and is a nun-in-training who loves God. She enjoys her daily life in the convent, but one day her father suddenly appears and makes an unreasonable demand: "If you don't want the donations to the convent to be cut off, you must take your sister's place and live in the royal palace as a candidate for the king's consort." To protect the convent she loves, Elsie becomes a candidate for consort. She is bewildered by her unfamiliar life, and the king is a scary man, but... as long as she can pray to God, everything will be alright! The chaotic royal palace life of a carefree, tomboyish nun begins! (Source: Kadokawa, translated)