Digimon Frontier

As the battle between Duskmon & Beowolfmon raged on, Patamon was doing his best to lead the gang to Koji but Cherubimon had them trapped. Then Cherubimon took advantage of Koichi's amnesia and gave Duskmon his Beast Spirit. When Duskmon's Beast Spirit Evolved to Velgemon, he forgot what little he still knew and tried to destroy Koji. Thank goodness Ophanimon intervened in time to stop him and now Koichi remembers that Koji is his brother.