Chiyu Mahou no Machigatta Tsukaikata ~Senjou wo Kakeru Kaifuku Youin~ Novel

Dragged into an otherworldly summoning during an ordinary school day, Usato Ken finds himself transported alongside an attractive man and an equally appealing woman. Starting from strangers mere hours before, the trio must navigate this new realm together. As someone without any standout talents or abilities, Usato Ken assumes he'll be treated as a burden by his companions. Yet both greet him with unexpected warmth and acceptance, igniting newfound hope within him. Maybe this journey will turn out well after all. But fate has other plans. Unbeknownst to Usato Ken, he harbors a hidden magical talent of remarkable power. Awakening this dormant gift, he's plunged into a merciless ordeal that transforms hope into torment, masked beneath the deceptive name of "training."