Krystal is Satou's childhood friend, though her origins are far more complicated than a typical friendship. She arrived in his world as a child alongside her grandfather, though she was actually the princess of the magical realm Nokanatika, sent to Earth in hiding. When they first met, she struck a deal with young Satou: keep her secret about being from another world, and she'd be his best friend. He agreed without hesitation.
Growing up together, Krystal faced constant bullying from other kids who saw her as strange and different. Satou made himself her protector, always chasing off anyone who gave her trouble. The two became inseparable, attending the Summer Festival together and holding hands like any close childhood friends would.
Years passed, and Krystal developed genuine romantic feelings for Satou during their time together. Eventually, she was summoned back to Nokanatika to fulfill her royal duty: marry a man named Marse and grant him the power of the Ring King. The prospect of leaving Satou devastated her. But when Satou unexpectedly followed her through the teleportation gate back to her world, she was shocked and overjoyed. Her happiness was tempered, though, by the harsh reality of what awaited him—she knew the trials required to become Ring King would be brutal. In the end, she bestowed the Ring King's power on Satou instead of Marse, choosing him over duty.
Content compiled by AnimeList.moe from publicly available sources.
