Japan

How to...

Set up an Amazon.co.jp account to be able to order things in Japan. Phone number verification is required to do so, non-Japanese phone numbers work, but you may or may not be able to receive texts in Japan, and if it does, it may be inconsistent
Modify 2FA settings for any critical services (such as finance or airbnb) to avoid relying on phone numbers
- If you're eligible, register a Google Voice number to replace your domestic phone number

Avoid rooms where smoking is permitted
Book a minimum of 14 days ahead
APA Hotel is a bad experience and more expensive. but when booking late, it is sometimes the only option close to the city center.

Return room keys to check out
- There will usually be a hefty penalty if the keys are not returned
You can usually pay 1000-2000¥/hour to get late checkout as late as 1pm-2pm

If your phone supports eSIM, purchase and install an eSIM profile from these providers:
- Airalo, on the KDDI/SoftBank network - more popular with tourists, cheaper and more convenient
- Sakura Mobile - on the NTT Docomoco/IIJ network - more popular with locals, more expensive but generally faster overall, tends to struggle in areas with lots of locals
If your phone does not support eSIM,
- you can purchase a physical SIM card from a local convenience store. Roughly 1 in 4 konbinis have them, ask for a "sim kado." It takes roughly 15 minutes to find a convenience store with one in Tokyo. Airport SIM cards are very expensive and the Keisei Express from Narita has free wifi.
- or you can purchase a physical eSIM to SIM card adapter. It ships from Germany, so it's best to do this ahead of time or while using a different solution
Free wi-fi is common in Japan. All Lawson convenience stores have free wifi. Many of them require verifying an email. Some commercial streets, especially around youth-oriented areas like Akihabara and Shinsaibashi, offer high-speed free wifi. The Japan Wi-Fi Auto-Connect app automatically connects you to nearby wifi networks without needing to verify an email and connects you to new ones as you move, but it consumes lots of battery life. Caveat: Shinkansen wi-fi tends to be fairly slow and only good for basic browsing and low bitrate calls.

Most hotels have an Ethernet port, you can purchase a USB-C to Ethernet active adapter. The Ethernet speed is usually somewhat (up to 2x) faster than the Wi-Fi speed.
Manga cafes are the best way to temporarily access low-latency and fast internet, up to 800Mbps