Honkai: Star Rail: A Shattered Heart, a Body Ablaze with Fireflies

[Nearly invincible + single heroine: Firefly + shadows + a little slow to warm up + guaranteed sweetness] Hidden in the shadows of the world, he sees the truth for what it is. He is both a witness to the world and the one moving its pieces. The shadows grant him immense power, but also curse him with loneliness. He silently endures it until one day he dies. But when he looks back, the girl, bright as a firefly, smiles and raises her right hand to tell him, “I've always kept our promise.” Ye Qing smiles and nods, tenderness still in his eyes, just as before. Only this time, Ye Qing knows that their overlapping shadows are no longer alone. Neither is he. (He wasn't the only one who fell in love amid that sea of flowers.)