Staying in Japan for 3 Months

Hello everyone!

I’m planning to stay in Japan for 3 months, starting early next year. I’m mainly considering Tokyo but would love to hear suggestions for other great places to stay as well.

Here are a few questions I have:

1. Best Places to Stay in Tokyo: I’m looking for recommendations on neighborhoods that would be convenient for a longer stay. I’m interested in good food, ease of public transport, and a safe environment. I've been thinking Ginza!
2. Finding Accommodation: What’s the best website to find short-term rentals or furnished apartments in Tokyo (or other parts of Japan)? I’ve heard about Airbnb, and have looked on other websites, but I’m open to other suggestions.
3. Health Insurance: What’s the best way to handle health insurance for a 90-day stay? Is there a particular provider I should consider? Do I need to apply for anything special since i'm staying that long?
4. General Advice: Any tips for someone coming to Japan for the first time? Things I should be aware of, or things I shouldn’t miss? I'd love to hear your thoughts on what would make the experience smoother and more enjoyable.

Thank you in advance! Any help or advice would be greatly appreciated!