けったろ (romaji: Kettaro) is a japanese singer who covers vocaloid and anime songs. He posts his covers in nico nico douga. His Nico Nico Douga mylist page can be found here. He started uploading cover songs after hearing タイツォン's work, unknowing that they were childhood friends.
Kettaro is most famous for adding rapid-fire singing to his covers that added dynamics to the song he sang. This technique can be heard in VOiCE