Rough translation (note that this is a very rough version, plus most japanese emotional songs don't make sense when directly translated):
Thinking about it far, far back
The future was shining everywhere
Beneath a beautiful blue sky
We were only afraid slightly.
The window is dyed in a familiar colour.
If we keep heading forwards will we meet again?
The future continues to infinity
Beneath the big signboard,
We were looking at the changes of our era.
To the people we'll never meet again there
We'll open a window.
Thinking about it far, far back
The future was shining everywhere.
And beneath a beautiful blue sky
We were sleeping forever.
Those people we loved long ago
It looks like a child will be born in winter
Those things that were certain long ago
We would like to question them.
Those things we could never forget
Are like mementos attached to a photograph.
Those things we couldn't do,
I will remember them fondly.