In role-playing games, slimes are usually the easiest monster to kill, and because of that, they yield few experience points. But what would happen if you live long enough to keep defeating them for 300 years? After many years of being a corporate slave, Azusa Aizawa abruptly passes away due to severe exhaustion. Seemingly headed for the afterlife, she meets a goddess who bestows her with immortality alongside a peaceful life in another world. There, Azusa enjoys her days tending to her farm, protecting the nearby village, and killing about 25 slimes per day—a routine that continues for at least three centuries. However, this rather monotonous cycle begins to change when Azusa suddenly finds out that she has reached level 99—the maximum possible level—from slimes alone. Despite desperately trying to hide this fact in fear of ending her slow life, rumors of her strength spread nevertheless. Soon enough, various people throughout the continent, like the dragon Laika and the elf Halkara, start to appear at her doorstep—some seeking a battle, others asking for her assistance. Meeting friends and acquaintances who soon become family, Azusa finds she can live a life far better with others than when she was alone.

After Mash Burnedead's clash with Magia Lupus, the secret about his powers is now out in the open. The short-lived celebration ends when the Bureau of Magic summons Mash before an audience of Divine Visionaries, who collectively decree Mash should reap the consequences and die. However, an evil shadow organization called Innocent Zero hijacks the inquiry to demand that Mash be kept alive. Mash proves that he is capable of dealing with Innocent Zero, but the Divine Visionaries' verdict remains unchanged. Luckily, Mash finds unexpected allies in Divine Visionary Rayne Ames and Headmaster Wahlberg Baigan, and they successfully defer his execution until Innocent Zero is defeated. Mash is now allowed to live under one condition: he must be selected as the Divine Visionary candidate by the year's end.

Naoya Mukai is having the time of his life after his childhood friend Saki Saki finally accepts one of his countless confessions. Ensuring that their relationship will stay strong, he spares no effort in showering affection to his now beloved girlfriend. However, one afternoon, another girl named Nagisa Minase suddenly confesses to Naoya following months of preparation. Even though he politely rejects her, Nagisa's irresistible charm and determination continue to attract Naoya. Wanting to fulfill both Saki and Nagisa's desires, Naoya ends up proposing a crazy idea—to date the two of them simultaneously, with both girls fully aware. This unprecedented state of affairs ultimately causes wacky and hilarious situations in whatever they do to keep their unusual relationship going.

Hikari Hanazono has always been able to do things that normal people cannot. As a child, she assumed no one could beat her—until she met Kei Takishima. Thinking she would win, Hikari challenged him to a match. But things didn’t go as planned; she lost not once but each time she rechallenged him. From that point on, she has sworn to best Kei at everything, ranging from academics to athletics. To achieve her goal, Hikari enrolls in the same school as Kei—Hakusenkan, a prestigious institute for the wealthy. As a pair, they hold the top two rankings in school and are among seven of the academy's best students in a class known as Special A. While Hikari treats Kei as a rival, she is completely oblivious that he harbors hidden feelings for her. Together, the members of Special A deal with competition, friendship, and just a bit of love.