Great concept of slaves not being soulless dolls but Sorte? Her antics are just too much - she shold not be able to hurt/ harm her master given there is a slave-contract.
Personality-wise MC is a wimp - start over in another world as an alchemist 😃
Get attacked by an adventurer bc the guy is stupid and take the accusation 😞
Being saved by the ex-machina guild master threatening to never sell potions again - he begs the GM to go lightly on a guy that was ready to kill him 😵
As recompense, the top female adventurer becomes his slave (he intially complains about that) 🙄
-> since the hot chicks side-show tags along, she becomes a slave as well and he just lets her abuse him (no, of course a Japanese Isekai-ist would never discipline a disrespectful slave for they have a liberal culture) 😳
Enter the slave merchant that somehow has a top-tier female slave being wooed by a self-important noble
-> in order to not sell her to the human trash our MC suddenly develops strong enough feelings for her to even risk his own freedom in earning enough to buy her 🤣
MC gets a nice house as a side effect of the trash noble being trash, decides to live there with his now 3 slave-girls (one of them deserving a beating before anything else)
-> cliche "washing master's back" bath scene ensues on the first eveing and MC is embarassed?
Cocky slave girl enters the bath, demanding him to leave -> MC is stupified and endures physical violence that should as per slavery contract be impossible 😠
As
@Roadrunner9000 said, author sacrifices their own world's logic for things to conveniently happen while MC is passive in almost every plot development so far (only thing active was the invention of vibrator and him actively seeking out a business partner)...
As far as foreshadowing is concerned: when the trash noble's step sister suddenly came onto MC on their first meeting, we knew she'd be trouble before eventually being added to his harem...