Not an Angel(2019)

Cheonsaga Aniya

Father Daniel is a new teacher at Kaebiji Private High School, a school that is known for being a dump where all the local delinquents gather. He is adjusting to his new life well until one night when he stumbles upon a woman while on patrol… and finds her beating a man. Sensing that something is off, Father Daniel reports the incident to the faculty the next day, only to realize that the woman, Miss Sasha, is also a teacher at the school. A strange relationship between a devoted priest and a kind teacher both disguised as angels begins...

(Source: WEBTOONS)