The history of Hatsune Miku begins in 18th-century Hetalia Italy.
There’s this famous Italian dude, see, called Bartolomeo Cristofori, whose main area of skill was in making instruments. And not just any instruments—keyboards, which at the time were these horribly tinkly little things where doinky featherquills plucked at an array of strings to create a metallic jingle-jangle effect. This is known as “Baroque music.” What Cristofori did, as part acoustician and part mechanical engineer, was to develop a hammer system that could strike strings at different forces, allowing the performer to play soft (piano) or loud (forte). So everyone called it a pianoforte, in Italianese. Of course, you and I and everyone else now know Cristofori’s invention as the piano.
When Italia invented the piano, they opened the door to Japan inventing Hatsune Miku.