The quest/map "Snow Dragons" contains the second star, or, your 5th character.
/ Second /
/ Star /
To find the second star, you must first head north to the area with an Inn. once you are there, head right 1, down 1. You will see trees blocking the sourthern path, however, you can pass through it diagonally Do so, and you will find a western path blocked by some trees. Bomb them, and you get some gold and a star. (I advise you get a Warrior character, because I was stupid and got a mage, only to find that he kept dying because there was no one to guard him.)