7日間でコードを覚える
day1 root 7days chords master
day2 black keys 7days chords master
day3 root+5th 7days chords master
day4 octave + 5th 7days chords master
day5 major and minor 7dats chords master
day6 sus4 aug dim 7days chords master
day7 slash chords 7days chords master