To learn Maretu - ダーリン chords, your first step should be understanding these chords - Bb, Ebm, Gb, B, Ebm, B, D and Ebm in sequence. I suggest starting at a calm pace of 43 BPM, and as you gain confidence, approach the song's BPM of 87. Set the capo considering your vocal range and favored chords, aligned with the key: Eb Major.