In Black Clover, some magic knights run out of mana quickly after a few spells and others can use a lot of spells because "they have a lot of mana". How does this people to have a lot of mana? Can they train to increase it? Is the mana you are born with the only mana you'll ever have?
To summarize the question, Is it possible for a magical knight to increase his amount of mana in Black Clover?