Spoiler.
He did buy slaves, but he only buys them to work. Reason why it need to be a slave is because he needs to make a magic contract that will force them to never tell anyone about his online grocery skills.
Those slave are the ones who transfers the hair producs to another container because it became high in demand.
And I think it was a good choice he bought slaves rather than regular workers because he pitied them and for safetyas well.. And if you think it was wrong that he bought sex slaves, he did not do anything to them. He just made them as regular workers like maids.
And after buying them, he goes on to travel as always and telling them the things they need to do, he just left the slaves at his house (mansion).
Also there is a kid who fell in love with him but that is not a love interest, it is just a fleeting emotion because he is their saviour. Her entire family was a slave and he bought everyone of her family just to keep them together and bought them clothes and feed them great meals which is uncommon. All of the slaves where happy because he was the one who bought them and he treats them as great.
Also, because he was given a blessing of a thousand years to live by the God of creations, and if you think that way with Fel, Dora, Sui, and Another ancient dragon who will stick to him for 300 years before going back to sleep again. They'll just travel/ adventure around the world and he'll be single for life.
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i just got spoiled under a felmuko doujinshi comment sec that he’ll buy a slave in the novel WOW i should have NEVER paused watching kusunoki’s garden of gods mid-watch to reread the dj and read the comments.