Zapp Goodfellow, a pack mule with only a storage skill, is expelled from the Golden Wind, a top-tier adventurer party. Falling into a pit and facing a dragon, he miraculously survives by storing the dragon's breath. He then uses his storage skill and the water from a healing spring to become incredibly powerful. Even when asked to rejoin his old party, he refuses, preferring his new life with cute companions. His peaceful days are interrupted by various challenges, including encounters with four beautiful adventurers, a self-proclaimed northern demon lord, and a fairy. He embarks on a journey to the Eastern city-states, makes new friends, and enjoys a slower life, training, fighting monsters, and enjoying delicious food. However, his peaceful life is threatened by the appearance of someone claiming to be the emperor. The story continues with new trials and adventures.