Smartphone In Another World

After being hit by a truck in his previous world, our MC awakens in a fantasy world as the son of a small shop owner.

Because his parents died, he had to discontinue his education for a year or two to handle their shop while waiting for his big sister's who's only have a year before she graduated.

A system appears and assigns him his first task:

[Sell 10 smartphones within a week.]

"First and foremost, how am I going to market this? Before I died, I was just a regular high school student."

"That is your problem, host."
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Witness how an unnecessary character like him would become the protagonist of his own story.