The more he carries, the stronger he becomes! An unmatched fantasy by the weakest adventurer duo!

Ryuk, a boy with a unique skill "Porter," which allows him to carry a massive amount of items, was being exploited as a chore boy for the S-rank party "Black Lion of Foresight." One day, the party managed to acquire a storage item more convenient than Ryuk's skill, thus no longer needed, Ryuk is banished inside a dangerous dungeon. Despairing in this hopeless situation, suddenly he meets a shrine maiden girl, Mio — and then?