I took piano lessons through pretty much all of grade school, and I used to mess around with an old Casio keyboard that let me record and play back stuff so I'd make arrangements of songs I liked on that! So when I got into using Vocaloid in 2009 I already had the hang of arranging MIDI tracks, and even though it took me a bit longer to actually try composition and songwriting (I did covers & remixes first) that's kinda what all led up to it!