Who sang this song "If"?

The lyrics of Xidan Girl's "If" is not this one or that one are as follows

Who said goodbye first on that day

Who said goodbye on that day Don’t miss those lonely nights anymore

Those pasts that can’t be returned

But now they are all pictures in memory

Who is still missing you in this year

Who is returning to the familiar place in this year

Those yellowed photos

Those helpless times tearful eyes

And now the dream that has become a regret is spreading

If there is tomorrow

I will wait for you until this day

Let We complete our unfinished wishes

If there is tomorrow

I will keep you in this moment

Let us become an eternal picture

Who is returning to a familiar place in this year

Those yellowed photos

Those no-one Suketoki's tearful eyes

And now the dream that has become a regret is spreading

If there is tomorrow

I will wait for you until this day

Let us complete our unfinished wishes

If there is still tomorrow

I will keep you in this moment

Let us become an eternal picture

If there is still tomorrow

I will wait for you until this day

Let us complete our unfinished wishes

If there is still tomorrow

I will keep you in this moment

Let us become an eternal picture