So, I did a similar trip to Kyoto a few years back with my old 80D, and honestly, walking those 15k+ steps with the stock strap was a huge mistake... my neck was basically dead by day three. For your 90D, I highkey suggest ditching that stock strap immediately before you even pack your bags. I've tried a few setups for long treks. First, there's the Peak Design Slide Camera Strap. It's great cuz it uses those little anchors and the seatbelt-style material slides over your clothes reallyyy easily. But, if ur carrying that heavy Canon EF 24-70mm f/2.8L II USM, you might want something that distributes weight better. I actually prefer the BlackRapid Sport Breathe Camera Strap for long days. It sits across your shoulder like a messenger bag, so the weight isnt pulling on your neck. The downside is it screws into the tripod mount, which can be annoying if you swap to a tripod often, but for walking? It's a lifesaver. For batteries, definitely stick with the official Canon LP-E6NH Lithium-Ion Battery. I tried some cheap knockoffs once and the discharge rate was super inconsistent, especially when using Live View which eats juice like crazy. Since the 90D doesn't support internal USB charging, I suggest the Nitecore UCN2 Pro Dual Slot USB Travel Charger. It lets you charge two batteries at once from a power bank in your bag while you're walking between shrines. Bag-wise, look at the Peak Design Everyday Backpack Zip 15L. It doesnt look like a typical "shoot me i'm a tourist" bag and the weather sealing is solid for those random Japan rain showers. I usually just carry a Giottos Rocket Air Blower for dust; honestly, avoid a full VSGO Camera Sensor Cleaning Kit unless you're in a clean hotel room. Lesson learned? If your gear is uncomfortable at hour two, it'll be actual torture by hour ten. Prioritize that strap comfort first!! gl with the trip, Japan is amazing! peace.

Seconding the recommendation above! Just found this thread and had to chime in cuz stock straps are the absolute worst. So, basically, the main issue is weight distribution. Stock straps focus all that DSLR pressure on a narrow strip of your neck, which is a total disaster for 15k steps. In my experience, you definatly need neoprene to absorb the "bounce" of the 90D. The OP/TECH USA Super Classic Strap-Uni-Loop is a total steal at around $22 and works wonders for comfort. Also, Live View is a massive power hog cuz the sensor is active constantly. Tbh, I'm usually cautious with off-brands, but the BM Premium LP-E6N High Capacity Battery 2-pack (usually $28) is a solid budget choice. For a bag, the Tenba Skyline 13 Shoulder Bag is around $80 and it's pretty sleek and weather-resistant. Dont let the low price fool you, it's realy durable. TL;DR: Grab an OP/TECH USA Super Classic Strap-Uni-Loop for comfort, BM Premium LP-E6N High Capacity Battery spares for power, and a Tenba Skyline 13 Shoulder Bag to stay low-key.

So basically, compare Wasabi Power LP-E6NH 2-Pack ($30) vs official Canon LP-E6NH. Wasabi's cheaper/reliable; official is safest. I'd go Wasabi. Also, get an Altura Photo Rapid Fire Neck Strap! be careful.

For your situation, r u looking for premium brands like Think Tank or more budget-friendly stuff? also, what's ur actual budget for the bag? prices vary *sooo* much, right?