Dont worry about feeling stuck, honestly we all start there. That kit lens is definitely the main reason your shots look like a phone... it just doesnt have the glass to create that depth you're looking for. For a trip to Japan with an a7C ii, you want something small that stays out of the way but performs. The Sony FE 35mm f/1.8 has been my go-to for a long time and I'm still incredibly happy with it. It works well for street shots and food because its wide enough to capture the vibe, but at f/1.8 you still get that beautiful blurry background for portraits. Its super fast to focus too, which helps when you're moving around a lot. If you want something a bit tighter, the Sony FE 50mm f/2.5 G is another one I've had great results with. Its part of their compact series so it fits the small body of the a7C ii perfectly. The background blur is nice, but you might find it a bit cramped for food shots across a table. Comparing them, the 35mm is way more versatile for travel. An 85mm is amazing for portraits but you'll be constantly backing into walls in narrow Tokyo alleys trying to fit anything in the frame. The 35mm basically makes that camera feel like the pro tool it actually is. Tbh, just grab the Sony 35mm and you'll be set for the trip. It fits your budget and the results are gonna blow your iPhone out of the water.

don't feel bad, the a7c ii is a beast but the kit lens is basically just a placeholder to get you out the door. had a moment to think about your $600 limit and it's actually a great budget for some high quality glass if you know where to look. real quick tho... when you're taking photos of your wife, do you usually like to stand pretty close to her, or do you prefer being further back? that distance really dictates whether a 35mm or a 50mm is gonna feel more natural for you. since you want food and streets, you generally want something wider so you aren't backing into traffic just to get a shot. here are a few that fit your budget and the camera size:

• Sony FE 35mm f/1.8 is basically the gold standard for your body. it is fast, sharp, and creates that blurry background easily.
• Samyang AF 35mm f/1.8 FE is the budget king. it performs way above its price point and is super light for travel.
• Sony FE 40mm f/2.5 G is incredibly small and built like a tank. it matches the a7c ii aesthetic perfectly, tho the blur isn't quite as heavy as the f/1.8 lenses. 85mm is usually way too zoomed in for narrow Japan streets or dinner tables. for that blurry look, you want a low f-number like 1.8 or 2.0. let me know about that distance preference and i can help you narrow it down further so you can get this sorted before your flight.

Building on the earlier suggestion, the Sony FE 35mm f/1.8 is a safe choice that wont break the bank.

• Fits your $600 budget
• Good for street/food
• Nice blurry background

Regarding what #3 said about "Building on the earlier suggestion, the Sony FE..."

• I agree that the 35mm focal length is the most logical choice for a one-lens trip, but unfortunately, many people overlook the technical compromises made in this price bracket. It is not as good as expected when you consider the atmospheric conditions you will likely face in Japan.
• Inadequate weather sealing is a significant liability in humid or rainy environments, leading to internal condensation.
• Lower-end glass often suffers from severe chromatic aberration, which manifests as distracting purple or green fringes around bright temple architecture.
• Slower autofocus actuators will frequently hunt in low-light street scenarios, causing you to miss the moment entirely. I have had issues with lenses that prioritize a low price point over mechanical reliability. Dont just look at the aperture numbers; if the build quality is flimsy, the lens wont survive the rigors of travel. Your high-resolution sensor will expose every optical flaw, so buying a budget prime might just lead to the same disappointment you're feeling with the kit lens. Focus on finding something with linear motors and proper gaskets.