Tentative Nanowrimo (as of last year, as I didn't finish) summary:

Elstia is the third princess of the bloodline kingdom of Kaliva, which means every member of the royal family is immortal. She lives a peaceful life inside the castle for her entire fifteen years of life, with her maid and dear friend, Yuna. But that all changes when her mother is dying due to an incurable sickness. On top of that, her father, King Frederick, decides he no longer wishes to be king.

How is Kaliva's new ruler chosen from among Elstia and her siblings? Per Kalivan tradition, the previous ruler must create a trial to select who is capable of being the next ruler. Frederick, valuing endurance and strength, decides to put his three children in the vast Dellwyn forest, to test their survival skills and battle with each other, since they can't die.

Every child is required to participate and put all their effort into the trial. Who doesn't want to be king or queen of Kaliva? But while Elstia's siblings both have special abilities and talents, Elstia has none. Who will win the Kalivan Trial?