Capt. Ronnajak Jutathep, eldest son of M.R. Ronnaphee, is entrusted with his deceased friend’s younger sister, Sunida. When he enrols Sunida at his alma mater, he runs into a former classmate, Jaipisut, who is now a teacher. Jaipisut barely tolerates Ronnajak, as she has no good childhood memories of him because of his teasing; but the two are forced to play nice together when Sunida has problems at school. Building a friendship with your arch-nemesis is never easy. Theirs is far more complicated when Jaipisut finds out she is adopted, and from the heirloom brooch left by her birth mother, she might be a Dhevaprom. Will Jaipisut’s connection to the Dhevaprom prove too much for Ronnajak to overcome, or will the two realise that what they have is worth fighting for? (Source: CH3+) Adapted from the novel "Jaiphisut" (ใจพิสุทธิ์) by Phraenat (แพรณัฐ).