Potion Uri no Shounen: Kare no Potion wa Jitsu wa Nandemo Naosu Densetsu no Elixir deshita

Ceel was a boy who made and sold potions used to treat light wounds and colds. However, unbeknownst to him, they were actually no mere potions, but the legendary elixir that can cure all wounds and illness. One day, he came across a noble girl who had trouble walking as she was so out of breath. Apparently, she had an illness which herbalists, doctors and even magicians couldn’t cure, but she recovered fully from Ceel’s potion. His potions became popular overnight, with adventurers and nobles fighting to get ahold of it. A new chapter of the kind-hearted boy’s life begins with his accidental elixir creation—.

(Source: Shueisha, translated)