The adventurer Shion, who possesses the "Translator" skill, the ability to understand the language of demons and animals, spends his days and nights on quests with his childhood friends in order to make the A-class party, Argonauts. However, he is suddenly kicked out of the party because his abilities are not useful in battle. Disappointed, Shion makes a new start as a solo adventurer, thanks to the encouragement of Angelina, the guild receptionist. Soon, several races join Shion's party, including a female slime swordsman and half-demon whose skills were deemed useless, and form a party of outsiders who are later described as heroes.