A Nobody's Way Up to an Exploration Hero

Kaito Takagi is a high school student with a mob character and low status. He's an ordinary explorer who hunts slimes every day in dungeons that appear in Japan. One day, he encounters a golden slime that he has never seen before. Baffled, he still manages to defeat the slime and get an extremely rare item called the "servant card," which can summon mythical beings and has a value of hundreds of millions. He then summons a valkyrie, a beautiful warrior maiden. Kaito starts his adventure to rise from being a mob to a hero. <em class=de-emphasized>(from manga)</em>

Synopsis from Anime News Network