Is the forest of fireflies sad? Who can tell me the plot?

Plot: The story takes place in the "forest of mountain gods" shaded by green. The little girl firefly got lost in the play and met Silver with a fox mask. They have established a beautiful friendship. Every year after that, fireflies will come to this mountain forest to look for silver, but the true identity of silver is an elf that will disappear once touched by human beings.

One day, Takegawa Hotaru told Ayin with regret that he couldn't come tomorrow because he was going to go home from school. He has only been to his grandfather's house in summer. Ayin told Takegawa Hotaru that she would come back next summer and wait for Takegawa Hotaru. So they are together every summer.

One day, Takegawa Hotaru, a naughty girl, hung upside down on a tree and accidentally fell down. Ayin quickly reached out and didn't catch her, because she would disappear when she touched her. Fortunately, Ayin didn't meet her Takegawa Hotaru, but at the same time she felt very sad because she couldn't touch Ayin.

Extended data

Story background:

The heroine Wuchuan is a human little girl. She spends every summer vacation at her grandfather's house in the country. At the age of six, she met the mysterious teenager "Ayin" and they gradually became good friends. We play together in the forest every summer.

Silver is a baby abandoned in the forest since he was a child. Poor Lord Mountain God, use magic to keep him alive. But you can't touch humans. If you touch human gold, it will disappear. Living in the forest, wearing a mask. Claiming to be a "monster" protected by monsters.

As the firefly grew up, her affection for Ayin gradually turned into ambiguous love. Finally, she attended the devil's sacrifice with Ayin, but after the sacrifice, she had an accident. When Ayin was about to disappear, she opened her arms and hugged the firefly.