A juvenile who has been bound over, pursuant to Title 15, section 3101, subsection 4, who is subsequently, as to the juvenile crime's adult counterpart, convicted and sentenced to a sentencing alternative involving imprisonment and who has not attained 18 years of age at the time of sentence imposition must be committed to a Department of Corrections juvenile correctional facility for an indeterminate period not to extend beyond the juvenile's 18th birthday to serve the term of imprisonment or any unsuspended portion until discharge from the juvenile correctional facility, and once discharged the juvenile must be transferred to a correctional facility in which adult individuals are confined to serve out the remainder of the imprisonment term or unsuspended portion, if any.   [PL 2019, c. 113, Pt. A, §2 (NEW).]