Complex sentence: They also have to face Nene's brother, Ewan Amano, who AxeKnightmon manipulates to become his human partner and join the Bagra Army on the notion that the Digital World is a game for his pleasure.
Split into simpler sentences: They also have to face Nene's brother, Ewan Amano, who Axeknightmon manipulates to become his human partner. Ewan joined the Bagra Army on the notion that the Digital World is a game for his pleasure.