Complex sentence: From 2002 onward, leading with Yamanashi a competition focused on "Japanese wine using only 100% Japanese grapes" began with anyone from a individual makers called Vigneron/ヴィニョロン to large producers competing with only the best quality domestic wines.
Split into simpler sentences: From 2002 onward, leading with Yamanashi, a competition focused on "Japanese wine using only 100% Japanese grapes" began. Open to anyone from a individual makers called a Vigneron/ヴィニョロン, to large producers competing with only the best quality domestic wines.