To jam and learn Back Number - Shiawase chords, your primary focus should be mastering these chords sequence: F#m, Bm, G, D, G, A and Bm. Start with a comfortable 74 BPM and as you become proficient, aim for the song's BPM of 148. With D Major as the song's key, tweak the capo to cater to your vocal pitch and chord likes.