Battle Frontier (Japanese: バトルフロンティア lit. Batoru Furontia) is the fourth Japanese opening theme of Pokémon the Series: Ruby and Sapphire. It debuted in AG135, replacing Pokémon Symphonic Medley. Its singer, Akina Takaya, is a relatively unknown artist. It debuted at the same time as a new ending, Pokémon Counting Song. The instruments-only version replaced the instrumental version of Advance Adventure in AG135 in the Japanese preview of the next episode. It was replaced by Spurt! in AG166. It was also used as the opening theme of Mew and the Wave Hero: Lucario in a different arrangement called Battle Frontier (Movie version). It was also used as the Pokémon Sunday ending from PS053 to PS059 and was then replaced by YEAH!.