In order to gain the chance to fuse demons into Hell Biker, you must defeat Matador after unlocking "Return of the True Demon", a side quest that was DLC in the original SMT 5. It's not that ...

Hell Biker in Shin Megami Tensei 5 Vengeance is a boss players can choose to go up against. Found in the DLC subquest that the protagonist must face, the monster can be confronted at the Shinagawa ...