How to buy USDT in Japan?

Could you please guide me on how to purchase USDT in Japan? I'm quite new to the cryptocurrency world and am looking for a reliable and secure way to acquire some USDT. I've heard that USDT is a stablecoin pegged to the US dollar, making it a stable investment option. However, I'm not sure where to start or which platform to use for the purchase. Could you recommend any reliable exchanges or platforms that operate in Japan? Additionally, I'm also curious about the legalities and regulations surrounding cryptocurrency trading in Japan. Is it legal to buy and sell cryptocurrencies in Japan? Are there any specific licenses or registrations required? Thank you for your help!