There are at least four bands named Arto.

(1) Arto is the alias of Claude Arto, member of Mathématiques Modernes, under which he released two singles in the early 80s on the legendary French label Celluloid.

http://www.discogs.com/artist/650516-Claude-Arto#t=Credits_All&q=&p=1

(2) Arto is an American indie band formed in Wisconsin in 2007. Their self-titled debut album, self-funded and recorded at Rock Garden Studio, was released in the summer of 2008. They are currently unsigned, but have opened for Someone Still Loves You, Boris Yeltsin, and Pushmi Pullyu.

(3) Arto is a Finnish punk band formed in Orivesi, 2004. Each member was studying there at the moment and they decided they should form a punk band, with each member playing the instrument they couldn't really play! The result can be heard on their album 'Turvanmitan edellä', an eight song record with total playing time of 9 minutes.

(4) ARTO is an instrumental rock band from Bologna, Italy. From their bandcamp: "ARTO is an electrified ensemble playing cinematic instrumental gloomscapes"
ARTO are:
Luca Cavina (bass)
Bruno Germano (left-handed guitar)
Simone Cavina (drums)
Cristian Naldi (left-handed guitar) Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.