Ecalir Seatto is a knight from Melromarc who happens to be the daughter of Seaetto, the Queen's right-hand man, and oversees the Demihuman protected village. She stands out among others in Melromarc for not discriminating against demi-humans. Initially, she questions Naofumi's methods, such as how he extorted from bandits, which becomes ironic later when she does the same thing herself. Ecalir is a noble person with strong beliefs and remains steadfast until her ideals are challenged by certain incidents.
Naofumi requested trainers to help his party improve their skills. As an expert in martial arts, Ecalir was asked to instruct Naofumi's slaves in Rock Valley to prepare for the next wave of enemies. Along with other experts, she helped improve the skill of Naofumi's group.
Ren looked down on Ecalir's skills and believed that as a hero and at a higher level than her, he had nothing to teach her. To prove him wrong, Ecalir challenged Ren to a duel using only pure skill. During the fight, Ecalir pushed Ren back, which upset him. In response, Ren used a skill that violated the rules of the duel. Although he technically won, because he broke the rules and admitted it after the Queen called him out on it, he lost the fight.
She then took on the responsibility of capturing Ren who was under the influence of his curse series by using her Hengen Musou techniques she had recently learned.