Recommended for first-time smartphone users under 12!
The Rakuten Mobile + Japan Communications SIM dual SIM option
When giving a child their first smartphone, most parents are concerned about these three things:
- They want to keep monthly fees as low as possible.
- They want to ensure they have a way to stay in contact with family.
- They want to be prepared for potential communication problems.
A recommended solution that meets these conditions is a dual-SIM setup using Rakuten Mobile (Strongest Kids Discount) + Japan Communications SIM (1GB plan).
Main Line: Rakuten Mobile (Strongest Kids Discount) (eSIM)
Rakuten Mobile is a very suitable carrier for children aged 12 and under getting their first smartphone.
Low monthly fees with the Strongest Kids Discount
Children aged 12 and under are eligible for the “Strongest Kids Discount,” which significantly reduces smartphone costs for low-capacity (up to 3GB) usage.
Children who have just started using smartphones often have low data usage at first, allowing you to provide them with a smartphone while keeping costs down.
33GB 480 yen (528 yen including tax)
*Applies to the Strongest Kids Discount and Family Discount, excluding other discounts. As of December 2025. Based on our own research.
*Applicable until the month before the 13th birthday. Contract must be in the child’s name.
*For users under 18, a filtering service (paid) contract is required.
Only Rakuten Mobile among the four major carriers! Contracts can be made in the individual’s name.
The Strongest Kids Discount can be contracted in the individual’s name even for those under 12.
Therefore,
- You can manage your child’s smartphone as an independent line.
- You can continue using the same line in the future.
Free calls with family using Rakuten Link.
Using Rakuten Mobile’s dedicated app, “Rakuten Link,” calls are free.
Therefore, by subscribing together as a family,
Child → Parent
Parent → Child
Calls can be made without worrying about additional charges.
Immediately after getting a smartphone, the “peace of mind of being able to contact by phone” is a very important point.
Secondary line: Japan Communications SIM (physical SIM)
Even for children’s smartphones, “communication stability” is surprisingly important.
Rakuten Mobile is attractive in terms of price, but the signal can be weak in some areas and locations.
Therefore, we recommend having a 1GB plan from Japan Communications SIM as a secondary line.
It’s not widely known, but their small-capacity (1GB) plan is incredibly cheap!
Japan Communications SIM Rational Simple “290” Plan: ~1GB 264 yen (290 yen including tax)
Data can be topped up at 220 yen per 1GB.
5-minute unlimited call option (+390 yen)
Japan Communications SIM uses the Docomo network.
In other words:
- Rakuten network
- Docomo network
You can use both networks on one smartphone.
