I remember the manga, I just can't remember the name.
It's about a kid. He has dark hair and eyes. We find out that he loves to draw and make art, but his parents don't support him and everyone thinks it's pointless for him to get into art (except one teacher who encourages him).
Suddenly, he gets transferred to another world, in a strange forest, with nothing but a pencil and sketch/notepad. (It was probably in a bag or something with other stuff but I don't remember.)
He draws an apple (I think) and it comes to life, through which he finds out about his skill. He then uses said skill to make a home, a pond (I think), furniture, some food & clothes, etc.
He also uses his skill to heal mystic creatures like unicorns/Pegasus (which made them his friends) and also uses it to heal his new human friend.
That's all I can remember and I swear it's real. I have read it. (By the way, the protagonist is a child in the entire part of what I wrote.)