Ryuuguu Fantastica

Legend holds that the oceanic Gates of Ryuuguu, the mythical Dragon Castle, open only once every seven years during the Houryou festival. It was during the last occurrence of this rare celebration that Yura discovered a boy named Nao alone on the beach. Though they shared no blood ties or prior connection, she chose to take him in, welcoming him into her life as her younger brother. For the next seven years, the two lived together in happiness, growing up side by side as family. Their peaceful bond seemed unshakeable, built upon the foundation of that fateful encounter by the sea. However, as the cycle nears its end and the next Houryou festival looms on the horizon, the atmosphere between them begins to shift. With the approach of the event that first brought them together, Nao starts acting strangely. His unusual behavior casts an unsettling shadow over their once carefree lives, leaving Yura to wonder what secrets the returning festival might uncover and how it will affect the brother she found on the shore so many years ago.