"I will no longer be working together with Sascha," tweeted the U.S.-based Japanese 21-year-old.
"I thank him for his work and wish him all the best in the future."
Bajin replied to Osaka with a tweet of his own.
"Thank you Naomi. I wish you nothing but the best as well. What a ride that was. Thank you for letting me be part of this."
Osaka hired Bajin in 2017 and enjoyed a meteoric rise during the time they worked together.
(Reporting by Andrew Both in Cary, North Carolina, editing by Pritha Sarkar)