Seijiro Makabe side quest question: I'm stuck
I'm in my first playthrough in Chapter 8. I just solved the pinwheel. I'm at the part in the quest where it says to investigate the Tachibana House. On the 4th page of that quest it mentions going under the bridge that connects the 2 houses. I have explored everywhere in that Tachibana House. I looked around for over an hour. The place is deserted at this point. I even tried going under the bridge, and all the way around the village to the Tachibana front. I still can't figure out how to unlock the door in the Tachibana House that when outside is up the stairs (just before the bridge with the water lady). I found that door inside the house though. Locked from both sides...
I could be mixing this up with the 5th crest, but I think I found another Folklorist note on the other side of the tree you go inside. Where you crawl through a brosh tunnel into an open grassy area.
From what I have read the quest is only able to be completed on NG+. I don't know why they would even offer it to me if it's impossible.
Is it able to be completed on NG or do I need to beat the game and finish it on NG+?