Jötunheimr is a realm from Book V of Fire Emblem Heroes. It's the home of the Jötnar, fairly tall people who praise traditional ways.
Long ago, the Jötnar of Jötunheimr ruled over the dvergar, until a young dvergr used his craft to build weapons which allowed dvergar to fight on equal footing with the jötnar and gain independence by founding Niðavellir. In recent times, the country is ruled by an unnamed queen, and a powerful blade named Gramr was offered to them by prince Ótr as a peace offering after relationships with them devolved to the point of leading to war.
Unlike Niðavellir, the jötnar of Jötunheimr have a culture rooted in tradition, and have excelled at combat since ancient times, despite generally disliking fighting. It has also been ruled by queens for generations, who are selected based on their strength in competition. This is due to the belief that the stronger the queen, the more likely it is that Jötunheimr can continue its lasting peace. The situation is no different in recent times, in which princess Nótt and her younger sister Dagr have been pitted against each other because it's what their mother and tradition demands.
In order to fight against Fáfnir, the Order of Heroes sends a missive to the royal family to obtain Gramr, which they agreed to meet, by meeting the eldest princess Nótt, at the Castle Barnstokkr. However, Dagr challenges the Order to prove her combat prowess for the title of queen, but promptly joins them on their travel once she's defeated. When arriving at Castle Barnstokkr, it's discovered that Nótt never intended to give the Order Gramr, as she'd fallen for prince Ótr of Niðavellir, who'd manipulated her into turning against the Order and Dagr by promising marriage. She captures Kiran, then hands them both over to Ótr. When she's defeated by the Order and Dagr, she's convinced to travel with the Order to compensate for her actions.
- Caste Barnstokkr - The royal castle of Jötunheimr. Gramr is kept here.
- Night Temple - Nótt's stronghold.
- Nótt - The crown princess of Jötunheimr and Dagr's twin sister who appreciates the finer things in life by prizing beauty and elegance.
- Dagr - The cheerful and big-hearted youngest princess of Jötunheimr and Nótt's twin sister who's ready for a scrap when the time comes.
- Unnamed Queen - Mother of Nótt and Dagr who upholds Jötnar traditions.
In Norse Mythology, Jötunheim is the realm of giants and frost giants that are enemies of both humans and gods. The realm is mostly depicted as a mountainous region with untamed wilderness and primordial magic.