Caught this thread a bit late but honestly, the Canon RF 24-105mm f/4 L IS USM is the most technically sound choice for your R5 II. I've been super happy with how the dual Nano USM motors handle focus tracking... it is just incredibly fast and reliable. Plus, the L series gives you full weather sealing which is a big deal if you get caught in a sudden shower in Kyoto. Since your budget is $1500, you actually have some cash left over. I'd suggest grabbing that lens and then picking up a Canon RF 50mm f/1.8 STM for those night walks in Shinjuku. Having that extra light for cheap is a total win. The 24-105mm weight balances perfectly with the R5 body too, so your neck wont be killing you by day three. If you need any more help with settings for the trip, let me know.

I would suggest being really careful with that Canon RF 24-240mm f4-6.3 IS USM on a body like the R5 Mark II. It is convenient for sure but you might want to consider how much digital correction is happening in the background. It basically leans on the processor to fix heavy distortion and vignetting at the wide end. For a once-in-a-lifetime Japan trip, you dont want your expensive sensor being limited by entry-level glass optics.

• Check the Canon refurbished site or reputable used dealers first to save around $300 on the Canon RF 24-105mm f4 L IS USM.
• Make sure to leave some of that $1500 budget for a tiny fast prime like the Canon RF 35mm f1.8 Macro IS STM for night markets and tight ramen shops.
• Be careful with the weight if you are walking 20k steps a day in Tokyo; the L series is pretty dense compared to the non-L stuff. If you find the 24-105mm f4 used for under a grand, you can grab a second lens and still stay under budget. Japan gets dark early in the narrow alleys and f6.3 on that superzoom is gonna force your ISO way too high. I would just stick to the higher quality L lens and crop in if you need extra reach. That 45MP sensor gives you tons of room to trim the edges without losing usable detail for prints. Better to have 50 sharp shots than 500 noisy ones because the aperture was too slow for the light.

In my experience, just get the Canon RF 24-105mm f4 L IS USM. I've tried many lenses over the years and that R5 II sensor is so sharp it really shows the flaws in the Canon RF 24-240mm f4-6.3 IS USM. Constant f4 is huge for dim temples too. Honestly, stick with the L glass, its totally worth it for those once-in-a-lifetime travel photos. You wont regret it...