character: hikawa_sayo, character: hikawa_hina, Medium shot from a side angle showing hikawa_sayo and hikawa_hina relaxing together in an outdoor hot spring (onsen) at night. Hikawa_sayo, with long aqua-green hair and green eyes, is submerged up to her shoulders in the steaming water, her expression serene and calm as she rests her arms on the smooth stone edge of the bath. Beside her, hikawa_hina, with short aqua-green hair and green eyes, leans back comfortably in the water, her arms floating loosely on the surface and a playful, relaxed smile on her face. The environment is a traditional Japanese open-air bath surrounded by dark volcanic rocks and lush greenery, with thick white steam curling upwards into the night air. In the distance, massive, vibrant fireworks explode across the dark midnight sky, reflecting shimmering colors of gold, red, and blue onto the rippling water's surface. The lighting is a contrast between the warm, soft glow of the onsen and the brilliant, flashing light of the fireworks, creating a peaceful yet celebratory atmosphere with a rich, deep color palette.
