《Only If》的詞曲作者是Agnes，由她演唱並作為聲優參與配唱。該曲目也是動畫劇情曲。歌詞是：
Only if I live to be a hundred
Only if I learn all the languages
Only if I conquer the ocean, all the mountains
Only if I save time for the sun
Oh I know, there’s still so much I don’t know
I will get tired, my heart might give in
Oh oh oh oh
Oh oh oh oh
I only hope
That there’s time for every moment that I lost
If there’s still one dream I can live my
Life so freely with my own choice
Only if I have my own choice
Oh I know, there’s still so much to do
I will get tired, my heart might give in
Oh oh oh oh
Oh oh oh oh
Only if I have my own way
Only if I make a difference
Only if I have my own space to run in
Only if I’m in the sun forever
Only if I find the words to say
To say how much every single thing you do really means to me
To make everything all right again, it would take a miracle.
Just wait and see, oh what tomorrow brings, with love and hope in my heart.
And if it all seems a bit too hard to take, remember this,
The best is yet to come.
It’s worth fighting for.
Oh oh oh oh.
Oh oh oh oh.
Oh oh oh oh.
Oh oh oh oh.
Oh oh oh.
Oh I know.
Oh I know.
Oh I know.
Oh I know.
I will get tired, my heart might give in.
Oh oh oh oh.
Oh oh oh oh.