Manga by author Sugiura Shiho

From Storm in Heaven: Rakan lives alone, and the plants in his garden grow so thick and fast that it seems like a jungle. One day a man, holding a gun made of wood, falls right down into his garden. He seems to come from another world, and he's searching for someone who can bring back the green into his own dark and inhospitable world.

From Storm in Heaven:Deep in a cave lies a demon trapped in ice who will eat any human who dares enter. The demon, Blood, waits for the human who will cry the purest tears, for the gem formed from those tears will break the spell that binds him. Then one day, a young man named Ishuca appears in the cave - and knowing that his weak heart will not last long, he has come to die. Touched by Ishuca's gentle nature, Blood gradually begins to change from the cruel, ice-cold demon he once was.