I accidentally tamed the weakest beast to become the strongest!

In Sol Village, there is a boy named Klein Keisler who got awaken with a rare class "Tamer" which is undeniably one of the strongest class throughout the history but–an accident occur and tamed a slime the weakest beast in the world.

That same day, his village got attacked by an unknown strong and brutal enemy. Gio, his inspiration for being an adventurer got killed along with his party and his beloved not blood-related sister "Cela" was caught.

Our protagonist luckily survive and change his identity as Arpada, he did not give up and remembers Gio's words that makes him to take a step forward with his beast to uncover the truth that happened in Sol village– the attacker and Cela's disappearance.