Look, I've tried many budget setups over the years and the Canon RF 50mm f/1.8 STM is basically a rite of passage. On your R100 it is gonna feel like an 80mm lens which is kinda tight for narrow Tokyo streets, ngl. You will be stepping into traffic just to get a full body shot sometimes. But if you want that blurry background for dinner photos, the Canon RF-S 18-45mm f/4.5-6.3 IS STM kit lens just isnt gonna cut it... it is way too slow for low light. My tip? Get the 50mm anyway. It forces you to think more about your framing and compositions. For those super tight indoor spots, just swap back to the kit lens for a second. Its a bit of a hassle but for under 200 bucks its really the only way to get that pro look on a budget.

Honestly, just go for the Canon RF 50mm f/1.8 STM right now! It is seriously the best bang for your buck you can find for the R100. I know people worry about the crop factor making it an 80mm lens, but for those dinner shots of your friends, it is absolutely killer. The blurry background you get at f/1.8 is miles better than anything that kit lens can do. That Canon RF-S 18-45mm f/4.5-6.3 IS STM is okay for bright daylight, but it honestly struggles so much in low light or indoors. You dont want grainy, blurry photos of your Japan trip! If you are worried about street photography being too zoomed in, you just gotta get used to standing a bit further back. It is actually a really fun challenge that makes you think more about your shots! Another tip is to maybe look for a used Canon RF 16mm f/2.8 STM later on if you want wide shots, but for a tight $200 budget today, the nifty fifty is the only lens that gives you that amazing pro look. I used mine for a whole trip once and barely missed the wide angle because the shots were so much sharper. Just grab it and start shooting before you fly out, you are gonna love it!