Zeolith wanted a chill life, but when he turned 15 his villages rule was that they had to go to the vocational school "Velciel" where each student will choose their profession. Zeolith wanted an easy job where he could laze around all day, but the only options he got were : "The Highest Peak of the Human Race【Hero】", "The Strongest Ruler 【Demon Emperor】", "The Title of the Strongest Magician 【Great Sage】", "And the last one "The Lowest Title, a Job For Scum【Slave Merchant】". None of the titles were a good option. He picked the lowest title 【Slave Merchant】, which is inconspicuous among them and seems to be easy to live.

But, He doesn't know it yet. It's the lowest occupation but it is the strongest for him and the most annoying-tiring ones. A harem struggle to be swayed by a variety of women, slutty alluring girls from elderly to younger ones who are his childhood friend's, the poisonous plantgirl, elves, cat ears adventurer, Loli Demon Lord, et cetera.

This is Tale of The strongest【Slave Merchant】unwillingly makes a big success!