The Japan Under-18 international will make the move to the Signal Iduna Park this winter as he aims to emulate Shinji Kagawa
The 17-year-old will join the Bundesliga giants on January 6, when he turns 18, and will start his European career in the club's Under-23 side, playing in the 3. Liga.
Dortmund have the option to make Maruoka's stay at the Signal Iduna Park permanent at the end of his one-and-a-half-season loan spell.
Maruoka follows in the footsteps of illustrious compatriot Shinji Kagawa (pictured), who made the move from Cerezo Osaka to Dortmund in the summer of 2010.
Kagawa quickly developed into an important first-team player at BVB and eventually earned himself a move to Manchester United in the summer of 2012 after guiding Dortmund to back-to-back Bundesliga titles.