Kazuma Satou heard a voice speaking to him and he found himself in a pure white room, confused at the sudden turn of events. The voice welcomed him to the afterlife, announcing that he had just died and that his life, though short, was officially over. As Kazuma looked around, he eventually came to a conclusion that the voice came from a girl whom he believed to be a goddess, judging from her clothes and appearance. He then began to recall the events that happened prior to his death.
As a matter of rare occurrence, Kazuma woke up early to buy a new online game he had been waiting for. Having successfully bought the game, he was set on his way home to play the game to his heart's content. On the way, Kazuma noticed a girl walking in front of him checking on her cellphone. Kazuma noticed that the traffic lights had turned green, but the girl hadn't noticed and continued walking. A large shadow approached the girl from the side. Believing it to be a truck moving at high speed, Kazuma knocked the girl out of the way and that was the last of his memories of the incident.
Kazuma then asked whether the girl he knocked away was still alive. The mysterious goddess answered that she was alive though having sustained a broken leg. Initially relieved that his death had not been in vain, he ended up lost for words when the blue haired goddess says that the girl he saved would have been fine had he not knocked her away, revealing that the large shadow was not a truck but a slow moving tractor. The goddess continued to ridicule him by revealing that he died due to the shock of believing that he had been run over by a truck, a death so silly and also the first she had seen in her line of work. She further added that Kazuma actually wet himself at the time of death and the hospital staff burst out in laughter when they saw what happened to him. Made even worse when the goddess told Kazuma that even though his family members were informed of his demise, they actually ended up laughing their heart out after hearing his cause of death.
Just as Kazuma was clouded in denial over his pitiful death, the goddess introduced herself as Aqua. She then continued by explaining that she had been keeping watch over the Japanese people who had died young and she had a proposal for Kazuma to consider. One, he could simply choose to start his life over. Two, he could go to Heaven with the unfortunate implication of living a totally uneventful life for eternity. However, starting over meant Kazuma would have all his memory wiped, effectively erasing his existence to become something of a blank slate. Just as Kazuma was conflicted in what to choose with the scale leaning towards starting over, she unveiled a third option with a sheepish smile.
Like the games that Kazuma liked to play, there existed another world that was currently terrorized by a Demon King. His army's invasion forced the Fantasy World into a dire state as the locals killed by the Demon King Army were too afraid to return, causing the world to suffer. So, the Gods had decided to infuse new life by transferring souls from other worlds to the Fantasy World with the focus on those who had had the unfortunate life of dying young with all their memories and physical functions intact. As a bonus, also a way to prevent these new souls from dying straight out of woodwork, each of them would be given one thing to compensate for their reincarnation; be it a special skill, a talent or even a relic class weapon that would enable these reincarnated people to become powerful combatants instantaneously. Realizing that there would be language barrier, Kazuma asked what would he do about that. Aqua happily revealed that they would provide the support by implanting all the necessary knowledge into his brain, with the possibility of overloading his brain if he's unfortunate enough. Even though Kazuma pointed out the danger of the situation, Aqua just told him to overlook it. Even though the things still bothered him, he didn't really have much choice but to go with it for now.
Looking through all the selection of special equipment and skills, Kazuma quickly realized that each one of them was definitely game-breakingly powerful and seriously considered about his available options but Aqua got impatient with the delay and urged him to hurry up from time to time, stating that she's busy. Finally, infuriated by Aqua's actions, Kazuma decided on one thing to bring along with him. He chose Aqua herself out of spite. Before Aqua could fully comprehend what had just taken place, another winged goddess appeared and informed the two that she would take over Aqua's place. She then informed Aqua that she was only slated to return to Heaven after the two manage to defeat the Demon King. Also, Kazuma could have one wish fulfilled by the Gods should he save the Fantasy World. Thus, Aqua and Kazuma set out on their new adventures, with Kazuma laughing triumphantly at the bawling Aqua.
Kazuma was ecstatic when he found himself in an entirely new world where magic was abundant with untold adventures to be had. He was further excited by the sight of residents having Beast Ears and the passing beautiful elves. His excitement was immediately cut short when the sound of Aqua crying her eyes out resonated through the air, effectively pulling Kazuma right back to reality. With no starter equipment and the goddess was simply a useless load, he decided to seek out a bar as it's the most cliche place in a game where information could be gathered. Seeing that Kazuma was actually giving her the cold shoulders when she herself was a respected and worshipped goddess of this Fantasy World, Aqua tried to chastise him of his actions but Kazuma just gave her the cold shoulders and went on his own pace, to find himself a bar.
Thinking about what his mission actually was, he had to kill the Demon King, Kazuma came to a decision that he should at least try to reach the Adventurer's Guild first but Aqua didn't have any useful information. If anything, she lacked almost all form of normal information of this particular town despite being a Goddess. The reason she gave Kazuma was that this place was simply too insignificant for her to take notice. Kazuma had to ask a passing elderly woman for the direction to the Adventurer's Guild because he didn't want to approach a male for information and he's too much of a chicken at heart to ask the young females either. The elder welcomed Kazuma and Aqua to Axel, the Town of Beginning, where those aspiring to become adventurers would visit to sign up for the profession. She then pointed them in the direction of the Adventurer's Guild. After obtaining the needed information, Kazuma then led the way to the Adventurer's Guild with the two quarreling all the way. It was at this time Aqua decided to call Kazuma "Hikki-Neet" while Kazuma gave Aqua the nickname "Kuso Bitch".
The two were welcomed by a red haired waitress whose hair was cut short when they arrive at the Guild. Seeing how the building actually implemented a bar and the presence of well-armed personnel instantly got Kazuma's hope up. He explained to Aqua the relevance of becoming an adventurer and with her agreeing to become one, the two then proceeded to the counter to get signed up... to only realize that they didn't have the needed money to even pay for the registration fee. Faced with such sudden dilemma, Aqua decided to show him just how dependable she was and demanded a priest who was in the building to pay his due to her, the goddess of the Axis Cult. Unfortunately for her, he's actually a member of the Eris Cult and Aqua decided that she should just leave. Adding insult to the entire ordeal, the priest happily provided the needed sum for the registration in the name of Eris and kindly reminded Aqua that it's not a good thing to impersonate a goddess before leaving them be. This was a huge blow to Aqua's pride as she had been pitied by someone who worshipped Eris, a junior goddess, and he never believed that she herself was actually a goddess in the flesh. That didn't matter one bit to Kazuma as he cared only that they had the needed provision money to begin the adventurer's life he had always wanted and headed towards the counter for a proper registration.
After paying the total sum up front, Kazuma and Aqua were then given a small lecture regarding the concept of being adventurers, experience points, leveling up and the use of Adventurer's Card. Later, the two were required to fill in the forms with any needed details before they were led to create their Cards. Kazuma's status was revealed to be somewhat average with high Intelligence and unbelievable high Luck. However, the female staff who helped create his Card mentioned that Luck was simply a stat that didn't play a major role for anyone aiming to become adventurers. She even tried to sway him away from becoming one to become a merchant instead as Luck would have been more useful in business than monster killing. Aqua laughed at the revelation but Kazuma just wouldn't back down from his initial decision and settled with the lowest possible job available for adventurers, Adventurer.
Aqua instantly caused an uproar in the building when she had her stats read. It was revealed that she actually possessed overwhelming stats compared to any adventurers though her Intelligence was somewhat below average and her Luck was downright pitiful. Her Magic stat was the most prominent of all her available stats. Aqua could literally take on any available jobs that didn't require high Intelligence like jobs that branched off the magician class. Aqua eventually settled with the Arch Priest, an extremely versatile job that would have no problem to dispense healing and support buffs while taking a vanguard role on the battlefield. With this, everyone in the building cheered and the staff welcomed her wholeheartedly while leaving Kazuma all alone in the commotion.
After two weeks of simply preforming manual labor and sleeping in the stables, Kazuma realized that they were making zero progress in defeating the Demon King. Since Axel was the town of beginners, most of the monsters outside of its border had already been eliminated. Therefore, the income of an adventurer was hardly ever stable. Aqua, who had become immured in her construction job, finally remembered that she couldn't return to the celestial plane unless Kazuma defeats the Demon King. She reassured him that any task fighting monsters would be a breeze with her present, which convinced Kazuma to begin some light grinding tomorrow.
The next day, Kazuma, equipped with only a small short sword, was furiously running away from a giant frog. Hearing Aqua laughing at him, he mentally noted that he would bury this girl before going back. After finally begging for Aqua's assistance, he discovered, to his utter dismay, that she was even more useless against the giant frog. As soon as Kazuma turned around, he found Aqua almost about to be swallowed whole, with one leg dangling in the frog's mouth. Charging in with his sword, Kazuma managed to save her. Aqua, who was now a slippery mess, began to complain about being deified by filthy frog. While Kazuma was trying to cheer her up, Aqua once again charged at the frog by preparing to use God Blow, which represented her feelings of wrath as a goddess. At that moment, Kazuma remembered the guild telling him that physical blows weren't effective against giant frogs. As Aqua's fist sunk into the soft abdomen, she looked at the toad meekly and softly said that frogs were actually quite cute. Swallowed whole again, Aqua is saved by Kazuma after the second giant toad that stopped moving as it attempted to swallow its prey. The day's adventure ended with Kazuma bringing a wailing goddess covered in slime back to town.
After selling the giant toad meat, Kazuma discussed the need for them to add extra members to their party. However, he noted that nobody would likely join up with beginners that had little to none equipment. In response, Aqua remarked that her status as an arch priest would surely attracted a great crowd, since she could preform healing spells like Resurrection. However, both of them dejectedly realized that nobody had responded to their recruitment notice. Kazuma understood that it was likely because of their perquisite of only accepting high-class jobs and their condition of defeating the Demon King. As Kazuma was considering lowering the job requirements, they were approached by a little girl dressed in a classical witch attire and a eyepatch. The girl identified herself as Megumin, an archwizard that used the strongest spell explosion. However, due to the girl's short stature, Kazuma classified the girl as an loli and ignored the request.
After defeating Beldia, a party was thrown in the Adventurer Guild to celebrate. As Kazuma mentally debated if he should continue to fight against the Demon King's Generals despite his low ranking and status. However, just as he was about to collect the reward from the counter lady, he found out that Aqua's water spell had caused massive property damage throughout the city. The reward for defeating Beldia was 300 million Eris, but the compensation bill for the damages was 340 million Eris. Now stuck in debt, Kazuma cursed his situation as he steeled his resolve to defeat the demon king in order to escape from this imposturous world.