KDDI began offering au Hikari Plus at 9:00 a.m. on September 17, a home internet service that combines a fiber line and the au 5G network in a single router. The dedicated router works over au 5G from the day it arrives, and once the fiber line is installed it moves to speeds of up to 10 Gbps without any action from the subscriber. KDDI says this is the first service in Japan to switch between mobile and fiber automatically within the same plan.

No More Waiting for the Installation Date

The annoying part of ordering a fiber line is the gap between signing up and the installation appointment, during which the home has no connection. With au Hikari Plus, plugging in the hybrid home router is enough to start using internet and telephone service over au 5G. When the fiber line goes live, the contract status and the billing switch to fiber automatically, with no paperwork on the subscriber's side. Smartphones and other devices in the home keep their existing settings. KDDI holds a patent on this linkage mechanism (Japanese Patent No. 7853512).

KDDI states that this is the first service in Japan to switch both the network and the billing from mobile to fiber automatically in step with the installation status, based on its own research as of September 4, 2026.

Up to 10 Gbps Nationwide, Including Partner Lines

Speeds reach up to 10 Gbps nationwide for both houses and apartment buildings. In addition to KDDI's own fiber, the service supports partner lines, and at launch that means lines provided through the NTT East and NTT West fiber collaboration model. Being able to consider a 10-gigabit plan outside KDDI's own footprint is a meaningful step toward closing coverage gaps. The lines and speeds actually available vary by region, building, and facility conditions.

If the fiber line goes down, the router can fall back to au 5G and keep the connection alive. For now, though, that switch is not automatic: it requires a settings change in the web interface, unplugging the LAN cable, or restarting the router. Automatic fault detection is scheduled to arrive through a firmware update during fiscal 2026. For a service that sells itself on staying up during a disaster, the real test starts once that step happens on its own.

Wi-Fi 7 on Board, but 6 GHz Is an Add-On

The hybrid home router consolidates the fiber line, au 5G, Wi-Fi, and telephone service into one unit. It supports Wi-Fi 7 and the 6 GHz band, channel widths up to 320 MHz (twice the previous standard), and MLO (Multi-Link Operation) for using several bands at once. The built-in wireless LAN tops out at 9.3 Gbps under IEEE 802.11be and 2.4 Gbps under 802.11ax.

One caveat: using the 6 GHz band requires the Wi-Fi Pack, an option that costs 770 yen per month. The Wi-Fi Pack bundles Home Network Protection, which analyzes traffic inside and outside the home to detect malware infections on smart appliances and block access to fraudulent sites, along with nuisance call blocking for incoming and outgoing calls, public Wi-Fi for use away from home, and call forwarding for the landline number. In practice, the pack is part of the standard configuration.

Effectively Free While You Wait for Installation

Five plans are offered: Home 10 Giga, Home, Mansion 10 Giga, Mansion, and Wireless. As of September 17, the supported ISPs are BIGLOBE, So-net, and @nifty.

In the example KDDI published (Home 10 Giga, two-year contract, BIGLOBE), the monthly charges before fiber installation come to 6,270 yen: 4,642 yen for internet, 770 yen for the Wi-Fi Pack, and 858 yen for the router rental. The Hikari Junbi Wari discount takes off 5,500 yen and the Wi-Fi Pack Debut Wari another 770 yen, bringing the effective cost to zero. After the fiber line is installed, the subtotal is 9,658 yen, and the effective monthly figure works out to 6,806 yen once the initial-cost equivalent discount and au PAY Gold Card points are factored in. On the Home plan, which tops out at 1 Gbps, the internet charge is 5,720 yen.

Most of the discounts run for a fixed term: Hikari Junbi Wari for up to 4 months, Wi-Fi Pack Debut Wari for up to 13 months, and the initial-cost equivalent discount for up to 24 months. The two-year contract renews automatically, and cancelling outside the renewal window costs 3,102 yen. Subscribers can stack au Smart Value, the UQ mobile Jitaku Set Wari, the au Denki bundle discount, and up to 10 percent back in Ponta points through the au PAY Gold Card (11,000 yen annual fee), though the deeper the discounts go, the more the household depends on KDDI's other services.

Summary

au Hikari Plus fills the gap while a fiber line is being installed with au 5G, then moves to speeds of up to 10 Gbps without any action from the subscriber. It also offers a fallback during outages and Wi-Fi 7 support, but automatic fault detection is still scheduled for fiscal 2026, and the 6 GHz band and the security features depend on the 770-yen-per-month Wi-Fi Pack. For anyone who cannot afford a connectivity gap around a move, it is a practical option.