Honestly, ditching the kit lens is the best move you can make. The Z 40mm is super compact, but if you want real sharpness for Tokyo, you gotta grab the Nikon NIKKOR Z 50mm f/1.8 S. It is leagues ahead in terms of edge-to-edge clarity and contrast. Just be careful with the size difference since the S-line glass is much heavier than that tiny 40mm. Also, make sure to update your firmware before you leave because the autofocus tracking on the newer bodies really benefits from those tweaks. Seriously, dont even second guess the S-line version. Its the gold standard for a reason and you wont regret the extra cost when you see those files pop on your screen later.

Regarding what #1 said about ditching the kit lens, I agree that it is holding you back, but I have a slightly different take on your best path forward. I spent a few weeks in Shinjuku last year with the Nikon NIKKOR Z 50mm f/1.8 S and while it is undeniably a sharp piece of glass, it can feel a bit tight for street work when you are maneuvering through those narrow alleyways. You might want to consider the Nikon NIKKOR Z 28mm f/2.8 instead. It is significantly cheaper and puts the extra cash back in your pocket for your trip expenses. Technically speaking, the 50mm S-line is optically superior with its extra ED and aspherical elements, but be careful with the focus breathing if you plan on doing any video. I found that at f/1.8, the depth of field is so thin that missing focus by a few millimeters is way too easy, especially if you are shooting moving crowds. The 28mm gives you more room to breathe and keeps your setup incredibly low profile, which is key for blending in. Just make sure to check your firmware versions, as some older Z-series bodies had issues with focus hunting before the updates. If you still want that S-line quality, save a bit more and look for a used copy, but for a Tokyo trip, wider is usually better.

^ This. Also, honestly, the kit lens struggles because the aperture just stops down way too much, making it impossible to keep your shutter speeds high without cranking the ISO into noise-land. Saw this earlier but just now responding—you really need to prioritize glass that delivers actual resolution. While the 40mm is fine for casual stuff, it unfortunately lacks the high-end elements found in the S-line. I had issues with edge softness on that lens when shooting wide open. If you want pro-level results, you have to look at the optics in the Nikon NIKKOR Z 50mm f/1.8 S 50mm f/1.8 glass. It is much sharper. Quick tips for your Tokyo trip:

• Use a higher shutter speed than you think you need; mirrorless sensors are demanding.
• Turn off VR if you are on a sturdy tripod, but keep it on for street handheld work. Everyone here is suggesting the 50mm or the 40mm, but honestly, if you can stretch the budget, look for a used Nikon NIKKOR Z 28mm f/2.8 if you want more of a street-friendly field of view. It is cheaper and fits the street vibe perfectly. Just dont expect the same clinical sharpness as the 50mm S-line. Don't waste more time on the kit lens, it is definitely the bottleneck here.