Ousama Wa One: Shota No Yume Wo Miru

The dream was vivid and clear: he saw himself running through a forest, the trees blurring past him as he chased after a figure. The figure vanished, leaving behind a massive, ancient door adorned with runes that shone like fire. With a deep breath, the King-Adventurer shot an arrow at the door, and it opened, revealing a realm of darkness.