Magatsu

Tsukiharu's life was ordinary. He lived with his younger sister, Sayuki. They went through the same routines every day, argued over small things, worried about groceries, and tried to get through life one day at a time. Then the ground swallowed them. One moment they were home. The next, they found themselves in a world hidden beneath reality—a vast land of endless forests, ancient ruins, and dangers beyond imagination. Separated and lost, Tsukiharu's only goal is to find his sister and return home. But the deeper he ventures into this strange world, the more he realizes that his arrival was no accident. Something ancient watches him from the darkness. Something that should not exist. And somehow, it knows his name. As forgotten secrets begin to surface and the line between myth and reality starts to blur, Tsukiharu must uncover the truth behind the hidden world, his family's past, and the shadow that follows him wherever he goes. Because some doors, once opened, can never be closed.