BioSphere Medical Inc. inked a deal with Nippon Kayaku Co. Ltd. to distribute two of its products in Japan.

The Rockland-based biotech firm said Nippon Kayaku will distribute its HepaSphere and Embosphere products, tiny “microspheres” used in embolotherapy procedures to treat uterine fibroids, hyper-vascularized tumors and vascular defects.

The terms of the deal call for the Japanese firm to handle and pay for the regulatory process there, “including performing any clinical studies that may be required as a condition to product registration.”

Nippon Kayaku will pay BioSphere a $1 million “milestone payment” this year and subsequent payments of up to $3 million as additional registration and revenue milestones are met.