Ken Usato, an ordinary high schooler, wishes for something fantastical to occur in his unremarkable life. Such an opportunity arrives when he is transported to another world alongside Kazuki Ryuusen and Suzune Inukami, two prodigious members of his school's student council. Arriving in Llinger Kingdom, the three are deemed to be the heroes tasked with stopping the impending invasion by the Demon Lord's army. However, this is a misunderstanding—Usato was summoned by accident and, unlike his two friends, is not one of the heroes. Despite this disheartening revelation, Usato learns that he has an aptitude for the extremely rare healing magic. This catches the attention of Rose, the intimidating captain of the kingdom's Rescue Team, who forcibly takes custody of Usato to mold him into a full-fledged healer. As he undergoes grueling training under Rose's supervision, Usato resolves to become capable enough to protect his friends from the dangers of this world. [Written by MAL Rewrite]