The Heart Kingdom 「ハート王国 Hāto Ōkoku」 is a country bordering the Clover Kingdom. It is the home of Undine, the water spirit, who formed a covenant with the country's rulers. The current ruler is Princess Lolopechka, and she has entered into an alliance with the Clover Kingdom to invade the Spade Kingdom.
The Heart Kingdom lies to the south of the Clover Kingdom. This country of green and water is rich with resources. The people adapted to the country's strong natural mana and created unique magic. Generations of princesses have used the power of Undine to protect the country. With a Mana Zone that extends over the entire country, the princess herself can monitor everything going on in the country and even assist in sustaining its forests and crops by using her water magic and guards the kingdoms borders with powerful Trap Magic. Nobles of the Clover Kingdom are allowed to submit requests for entry and studying the country's magic.
The kingdom has its own system for rating a mage's skill and talent. It is divided into ten Magic Stages, with Stage Zero at the top and Stage Nine at the bottom. The Kingdom itself possesses five Spirit Guardians who are ranked as Stage Zero.