Chiyu Mahou no Machigatta Tsukaikata: Senjou wo Kakeru Kaifuku Youin

When ordinary high school student Usato happens to bump into student council president Suzune and classmate Kazuki on his way home. All three are suddenly swallowed up by a magic circle and transported to another world. The trio are summoned as heroes to save a kingdom from a demon king's army — but, only Suzune and Kazuki have what it takes to be heroes. Usato just happened to be dragged along for the ride. However, things turns around when Usato is discovered to have the rare knowledge of a healing mage. He is abducted by a woman who identifies herself as Rose, the leader of the life-saving corps, and drafted into her ranks. Source: ANN