>>530754369
>>530753279
The Trails series is notorious for this kind of thing. Zero no Kiseki & Ao no Kiseki especially, since they both take place with a giant hub city, and the outskirt cites are available most of the time too. You could spend an hour after every main story beat retalking to every NPC, even with the turbo features that were added. Tons of hidden quests that start only when you talk to specific NPCs at the exact right time, some of them even lore related.
There was a hidden side quest in Cold Steel 2 that I thought people were joking about for weeks until I picked up on the fact that it was real, and those innocuous side characters were heavily story important. Lots of people probably jumped into CS3 without ever knowing until it came up there as part of the main story.
Fucking love Trails.

The Crossbell duology (Zero & Ao) reminded me a lot of P2 for what its worth.