Guild no Zatsuyougakari ga Shin no Kuromaku Deshita: Kakureta Sainou de Anyaku Musou

Tenes, the illegitimate son of a high-ranking nobleman, grows up ostracized and isolated, but the only one who treats him kindly as family is Fiona, the daughter of the legitimate wife. However, a tears them apart... Labeled incompetent, Tenes is banished to the countryside, and Fiona becomes embroiled in a succession struggle for the emperor's throne. "I will protect her no matter what." With the skills of a [Hermit] abandoned by the gods and his quick wit, he challenges the twisted rules that plague the world, together with his strongest companions. A dull, errand-running boy—but actually, he is the mastermind behind a dark organization plotting to overthrow the world (?)!! (Source: Drecom, translated)