Mysticism apart, there are several elements in that sequence that may be real and others that are purely imaginary.
The conversation between ghost Banri and Reawakened Banri is imaginary, but the other elements are confusing...
- How the ring ends in Banri's pocket? It fell off the bridge. The ghost is soaking wet, implying that he did went into the river to get it, but the ghost cannot interact with the real world unless he is possessing Banri. Banri is dry when he hugs Koko.
- Linda's response: is it the real Linda that is delivering it (she could have ran after and caught up with Banri while he was discussing with the ghost) or just another figment?
- How long is that bridge? Is it a real landmark?