In my experience, prioritizing protection and power is the most methodical way to prep. Over the years I have found that high-quality basics are better than bulky grips. Focus on these:

• Leica M11 Screen Protector
• Leica BP-SCL7 Lithium-ion Battery
• Artisan and Artist ACAM-301N Silk Cord Strap The silk cord is incredibly secure for street shooting. I find an extra battery is essential for peace of mind while traveling.

Regarding #2, Ive been super satisfied with the Peak Design Slide Lite Camera Strap tho. Works well. It leaves budget for a SanDisk 128GB Extreme PRO UHS-II SDXC and a Leica Soft Release Button 12mm.

Wait, are you planning to do mostly night shooting or daytime street stuff while youre in Tokyo? Just curious because the weight really starts to add up when youre hitting 20k steps a day. Honestly, I had some issues with my kit on my last trip and it was not as good as expected... it really let me down when I was navigating the crowds. It actually reminds me so much of when I was wandering through Osaka looking for this specific vintage toy shop I read about online. I had the map pulled up and everything but the signal was so spotty between the buildings that I got completely lost. I ended up stumbling into this tiny woodworking studio where this old guy was hand-carving traditional masks. I spent like three hours just watching him work and he didnt speak a word of English but we just kind of nodded at each other while he polished the wood. It was way more memorable than the toy shop would have been, though I was starving by the time I found my way back to the main street. Anyway lol sorry I totally went off on a tangent there.

Commenting to find later

Jumping in here because i have a totally different perspective on how to kit out that M11 for a big trip! While silk cords look amazing, they can be a bit of a nightmare when you are trying to shove the camera into a small bag quickly or wrap it tight around your wrist. I actually think you should reconsider the strap choice and focus on ergonomics for those long days walking around Shibuya.

• The strap is everything. Look at the Rock n Roll Straps Classic Greek Leather Strap. It is so soft and flexible, way better for wrapping around your hand than a stiff cord! Love the way the leather breaks in and it feels incredibly secure.
• Forget the official grip. It makes the camera feel like a clunky DSLR. Instead, the Match Technical Thumbs Up EP-MX is an absolute game changer. It provides incredible stability for street shooting without adding any weight or bulk. The fit is so precise it wont damage the hot shoe at all, honestly it feels like a native part of the body!
• Get a high speed card for backup. Even with that internal storage, you want redundancy for a once in a lifetime trip. The Sony SF-G Tough Series 64GB SDXC UHS-II is basically indestructible and ensures you never have write lag during fast bursts.
• Protection. Instead of just a screen film, look at a half case like the Arte di Mano Half Case for Leica M11. It protects the base and sides from those inevitable bumps on the Tokyo subway while looking fantastic. You are gonna have an amazing time! That camera is a total beast.

Can confirm this works. Did the same thing on mine and its been solid ever since.