Updated: 2025-06-18 16:40:44
Planning your trip to Japan but overwhelmed by all the eSIM options? Words like “30GB,” “5 days,” and “Unlimited” might all sound the same—but which one actually fits your needs? This article is written for complete beginners. We’ll walk you through how to choose the right data amount, duration, and price—step by step. By the end, you’ll know exactly what to pick.
The first thing to figure out when choosing an eSIM is: how many days will you be in Japan?
Most eSIM plans are fixed-length: 5, 10, 15, 30, or 90 days. Important note: if your trip is 6 days, a 5-day plan won’t be enough—you’ll lose internet on the last day. We recommend getting a plan that covers your travel days + 1 just to be safe.
Quick tip: Some eSIMs start counting from the moment you finish installation, while others start when you first connect to the internet. Always double-check the usage details before buying.
Not sure if 30GB is a lot or a little? Here are a few examples to help you understand:
If you’re mainly using your phone for maps, web browsing, and social media posts, 1GB per day is usually more than enough. So for example:
Not necessarily. Many “unlimited” plans come with Fair Usage Policies (FUP). For example, a plan might allow 3GB per day at full speed—if you go over, your speed will be slowed down. Unlimited plans are great for heavy users or people who don’t want to think about data limits.
But if you’re just using the internet for maps and light browsing, even 15GB or 30GB can be more than enough—and they usually cost less.
Don’t just look at the price tag when choosing an eSIM. These factors also matter:
Sometimes paying a little more gives you much more stability and peace of mind.
Q: What if something goes wrong while installing my eSIM?
A: Do NOT delete your eSIM! Some eSIMs can’t be redownloaded if deleted. Always contact customer support first. For example, CDJapan Rental offers clear setup guides and support. Ask for help instead of trying to fix it on your own.
Q: Will my original phone number still work after installing an eSIM?
A: Yes! Most smartphones support dual SIM. Your eSIM will handle data, while your original number can still receive texts and calls (like verification codes from your bank).
Q: What if my phone shows no signal after installing the eSIM?
A: Usually, restarting your phone or toggling airplane mode solves the issue. If it doesn’t, check that the eSIM is enabled and set as the active data source. If you’re still stuck, contact customer support.
Q: What if there’s no signal in some areas in Japan?
A: Choose an eSIM that connects to a major Japanese carrier like docomo for the best coverage. CDJapan Rental uses docomo, which tends to be more reliable than international eSIMs.
Q: Can I share my eSIM’s internet with friends (hotspot)?
A: Most plans allow it, but some cheap eSIMs do not support hotspot sharing. Always check if “hotspot/tethering” is supported before purchasing.
Recommended article: Can You Share Japan eSIM Data with Friends? What You Need to Know
Q: What if I run out of data during my trip? Can I buy more?
A: Some fixed-data plans let you top up, while others don’t. If you’re unsure how much data you’ll need, an unlimited plan might be the safer choice.
Choosing the right eSIM is simple if you remember these three things:
If you’re still unsure, CDJapan Rental offers a variety of eSIM plans (30GB, 50GB, 135GB, Unlimited), all using Japan’s docomo network. You can purchase before your trip and get online as soon as you arrive—perfect for first-time users.
