The student was rushed to the hospital, where he required more than 50 stitches for his injuries.
A 43-year-old Singaporean man had arranged for the cough syrup to be distributed illegally to the two Yishun addresses.
The 35-year-old male driver was charged in court with multiple offences.
Two other people were assessed for minor injuries.
The cyclist crossed into the path of the bus, which was unable to stop in time, said Tower Transit.
The restaurant has been asked to suspend operations.
The restaurant was said to have been the subject of previous public complaints.
The deceased, who has been identified as a 64-year-old man, did not have any external injuries.
One netizen suggested that it could be a new driver who was too accustomed to using footpaths.
The victim, believed to be in his 20s, was visiting Japan with his mother.