I'm helping a friend find a webtoon she read three years ago.
What she remembers is that the main character is a red-haired boy with magical powers, but is keeping it a secret. A black-haired boy who plays baseball finds out and keeps it a secret too. The red-haired boy also has a grandmother who who has magical powers too.
Edit: More information
They wear modern clothes, his Magic he can make things float in the air, I think his pencil turns into a monster, his grandmother in real form is old,but in Magic form she's young and pretty. That's all my friend remembers so far