Birth Stones(誕生石) are gems the player selects at the beginning of the game for each of the five characters and determines the month your character is born in. Each birthstone gives each character their own unique attributes. During a battle you will notice a colored gem located in the middle of the cards which indicates which month they were born in. If the card used has a matching birth stone it will make a distinct noise when chosen and the power of the card used is doubled. Even weak Cards can be powerful if the birth stone on it matches that of the character. Another indicator of a matches is the flashing of the gem in the middle of the chosen card.