Melodious Japanese song I heard 10 - 12 years back that I wanna share with you folks

When did we realise we became adults? Do you remember how free you were from responsibilities, worries then? Well, this song reminsices that. The 1st time I heard this song was when I saw Doraemon: Nobita's little space war. Its song when bunch of folks are camping in a bunker to prepare for a fight. Everytime I hear this song, it truly brings out my emotions. I thought I'd search youtube for this song and understand the lyrics. Sharing you the song with Japanese lyrics and English meaning. I hope you find this song as amazing as I did especially if you are the type who like melodious and can reminisce yourself within the song.

Here goes - https://www.youtube.com/watch?v=tD0F5CiuHek