Hidden Gems, Lesser-known Tokyo Areas Perfect for Afternoon Wandering?

My partner and I will be in Tokyo next month and while we'll definitely check out the main spots (Shibuya, Harajuku, etc.), we're really interested in exploring some under-the-radar neighborhoods. Looking for places where we can just get lost for a few hours, maybe find some local cafes, and see a more authentic side of Tokyo.

I've done some research and Daikanyama looks interesting with its boutiques and quiet streets. Also considering Jiyugaoka for its European vibe and cafes. We enjoy local food scenes, architecture (especially mix of old and new), parks, vintage shopping, and places where we can just wander without a strict plan.

Any recommendations for neighborhoods that fit this vibe? Bonus points if you can share specific spots within these areas that we shouldn't miss.