彼方(かなた) is a poetic word meaning “far beyond” or “the distant reaches,” often used for something that feels remote and almost unreachable.
In the song, the bird disappears into 大空の彼方, “the far reaches of the vast sky.” Its literary tone and evocative imagery make it more memorable than the everyday word 遠く (far away).
Janne Da Arc open "GUILTY PAIN" like a disaster movie: 映画みたいなシーン綺麗な花火 (a scene like a movie, beautiful fireworks). Then you realise the "fireworks" are bombs. The playground the singer grew up in has turned to 瓦礫 (rubble), and nothing is left but 骸の山 (a mountain of corpses). The war imagery keeps coming: 冷たい鉄の雨 (a cold rain of iron), barefoot children with dried tears, and a TV that 憎めと教えた (taught us to hate) soldiers from some other country.
The narrator's answer is refusal. 僕は銃を手に取れない (I can't pick up a gun), he sings, and later 僕は天に昇れない (I can't rise to heaven). All he has is a pair of wings he wants to spread 世界中に (across the whole world) from この小さな島 (this small island), which reads as Japan itself. He admits 唄うことしかできなくて (all I can do is sing), and that honesty is what makes the chorus land. The last line is bleak and blunt: 神の国なんてどこにもない (there's no such thing as a land of the gods anywhere). For a learner, watch how often ない and できない show up: the whole song is built out of things the singer cannot do.