Hardest Ayu song to sing?

[alternarist]

after singing practically every ayu song that i noe of the shower, i feel that INSPIRE and JEWEL are the most difficult to sing.

INSPIRE - low notes are really low and high notes are really high. I can manage the tongue twisting choruses but i cant really reach the last note of every line in the chorus smoothly.

JEWEL - just cant grab the key well enough.. and there is a lot to sing. So i find it hard to sing till the end.