Fランク召喚士、ペット扱いで可愛がっていた召喚獣がバハムートに成長したので冒険を辞めて最強の竜騎士になる

召喚士兼冒険者のジェイは「トカゲの召喚師」と呼ばれ、周囲から嘲笑されていた。Jay, a summoner and adventurer, was called "the lizard summoner" and was ridiculed by those around him. Although he was a summoner, he was despised because the only summoned beast he could summon was a small lizard named Kyuk. Because of this, Jay could not form a party with anyone and continued to be a lone adventurer. One day, however, Kyuk suddenly grew up to be a huge and majestic dragon, Bahamut! Jay took this as an opportunity to start his own business as a courier. Jay carries out his work flawlessly under the creed, "I will carry anything depending on the reward. Before long, word of the "dragon knight of the courier" spreads throughout King's Landing, and everyone comes to depend on him! From the weakest summoner to the world's best dragon knight, Jay's fantasy life as a courier is about to begin!