When Ai returns from her grave, Sentarou witnesses her burning the village down, her eyes a shade of red instead of brown. As she does so, she sings the song she and Sentarou would sing when she was in hiding. Ai also seldomly sings this song whilst in the realm of eternal twilight, stacking flat pebbles on top of each other.
This song is called "Sakura Uta":
Japanese (Romaji) version:
Sakura no hana wa itsu hiraku?
Yama no osato ni itsu hiraku
Sakura no hana wa itsu niou?
Warau nana no ko asobu koro
Sakura no hana wa itsu odoru?
Utau nana no ko nemuru koro
Sakura no hana wa itsu kuchiru?
Shinda nana no ko noboru koro
Why do lovely flowers bloom from the cherry tree?
Children of seven, waking smile at the sun.
Why do fragrant blossoms stir in the mountain air?
Children of 7 laughing run through the woods.
Why do crimson branches dance in the village streets?
Children of 7 singing, call down the wind.
Why do wilting flowers fall from the cherry tree?
Children of 7 dying to wake once more.