Regarding what #2 said about "Honestly, Japan is amazing but the humidity can..."

• I've found dust to be the real enemy over there. Years of travel taught me that spots always show up at the worst times. I once spent an entire Kyoto trip cloning out sensor dust cuz I forgot a blower.
• Giottos Rocket Air Blaster Large
• Peak Design Slide Lite Camera Strap Black Ditch the grip. A good strap makes the X-T5 feel weightless during those long walks through Tokyo.

TL;DR: Skip the grip. Buy a PD power bank instead of multiple OEM batteries to save cash. In my experience, the extra bulk of a grip isnt worth it for travel. Just charge via USB-C using a Anker 525 Power Bank 20K 20W PD during breaks; its way cheaper than buying extra Fuji packs. Also, for storage, the Kingston Canvas Go Plus 128GB SDXC UHS-I V30 is a great budget pick that handles 4K just fine.

Honestly, Japan is amazing but the humidity can be a real pain for gear. I spent way too much on a fancy thumb grip recently and it just felt loose after a week... total disappointment. I think someone told me that the X-T5 sensor is super sensitive to dust too, so maybe grab a decent blower? Not 100% sure if that's actually true or just internet talk, but I always carry one just in case since I'm paranoid about spots on my photos. Regarding the batteries, yeah, the official ones are ridiculously expensive. I tried some cheap third-party ones and they bloated slightly which scared the life out of me... definitely not as reliable as I expected. I'd almost suggest just getting a glass screen protector before you go because those X-T5 screens seem to scratch way easier than they should, tbh. It’s kinda stressful trying to keep everything mint while traveling, ngl.

Wait, which lens are you actually planning to take? If its one of the heavier red badge zooms, my advice is gonna be way different than if you are just rocking a small prime. I really have to warn you about the third party battery route tho. I had some major issues with generic packs in my X-T5 recently... they were super disappointing and actually started swelling after only a few months of use. It makes me so nervous because if a battery gets stuck in your camera while youre in the middle of Japan, youre basically screwed. Reliability is everything on a trip like this. Instead of buying more batteries right away, I suggest getting a Nitecore FX3 Dual Slot USB QC Charger for Fujifilm NP-W235. It is way better than charging in-camera because you can see the exact voltage and health, and it lets you top off two cells at once from a wall plug or your power bank while you sleep. Also, grab a Expert Shield Glass Screen Protector for Fujifilm X-T5. I unfortunately used a cheap plastic film one on my last trip and the humidity made the edges curl up and look like trash within days. A solid glass one stays put and actually protects the screen from scratches when youre tossing the camera into a bag.