How many days should I ideally allocate for an immersive exploration of Osaka, Japan, to fully appreciate its vibrant culture, delectable cuisine, and historical landmarks? Is two days sufficient to traverse the bustling streets and iconic districts such as Namba and Shinsaibashi, or would three days afford me a more leisurely pace to savor local delicacies like takoyaki and okonomiyaki? Furthermore, should I consider dedicating an additional day for excursions to nearby attractions, such as the majestic Osaka Castle or the awe-inspiring Universal Studios Japan? What about the timing of my visit—would certain seasons enhance my experience, allowing for seasonal festivals or cherry blossom views? In contemplating my itinerary, how do I balance the urgency to visit famous sites while still allowing time to stumble upon hidden gems peppered throughout the city? Ultimately, what is the optimal duration to ensure a fulfilling journey, blending both adventure and cultural immersion in this dynamic metropolis?