The manager accountable for a business area's processes and systems, including how records are created and managed within them. This is why recordkeeping is not solely an IM-team job.
The business owner is why recordkeeping is not 'just an IM-team job'. Because they own the processes and systems where records are actually created, system changes in their area should not proceed without considering recordkeeping requirements.
IAR turns terms like this into working practice: assets classified against your disposal authority, stewarded by position, and ready to evidence.