Since this world started, many people died, but their souls stayed with us on earth, maybe, in far future, somebody will be able to collect all these souls and revive them, Yoshi always supported this theory, and tried to spread it to everyone that he met in his life, he felt like nobody else thinks the same, and people started making fun of him, there was only one person in his life that supported same theory, and that was his childhood friend Yuna, unfortunatly Yoshi never got to convince anyone else.