The fourth installment of Mega Man Battle Network Red Sun and Blue Moon, each with unique enemies, battle chips, souls, and characters. Take the role of the main protagonist, Lan, as he and his friend, Mega Man.exe, fight to rid the Internet of viruses and other cyber world enemies. Unlike previous games in the series, Mega Man Battle Network 4 focuses on a tournament system where players encounter a variety of enemies that must be defeated. A new Soul Unison system lets Mega Man transform into his defeated enemies.