Hi @west40texas
The hose is part ID #52 [https://www.bettervac.com/Hitachi-881675-Rilsan-Hose-Kit|Hitachi part # 881-675] (supplier example only to show part) as seen in the [https://www.mmtoolparts.com/media/diagram/files/EC12.pdf|parts list] for the compressor, which shows that it goes to "A", but there's no other indication where "A" connects to.
I think it may be part ID #64 [https://www.amazon.com/Sellerocity-Safety-Compatible-Hitachi-881-493/dp/B07584JP9G|Hitachi part # 881-493] (supplier example only to show part)
If you think that it may be the one, search online for ''Hitachi 881-493'' to find suppliers that suit you best.