Japon : la couverture mobile

Ce que veulent dire les chiffres de Japon

Deux nombres comptent et un seul est celui que tout le monde cite. Le débit habituel, 74 Mbit/s, dit à quoi ressemble un bon moment.

Le dixième centile, 21 Mbit/s, c'est celui qu'il faut lire. C'est le débit du dixième le plus mauvais de la journée, quand l'antenne au-dessus de la gare est saturée et que tout le monde autour de vous est dessus. Un pays à médiane haute et à plancher bas, c'est un pays qui marche à merveille jusqu'au moment où vous en avez vraiment besoin.

Si le voyage dépend des appels vidéo ou du partage de connexion, organise toi en fonction du chiffre en heure chargée plutôt que du débit habituel.

Ce qui se passe en Japon quand le réseau est saturé

La congestion n'est pas une panne, c'est un mardi soir. La question est ce que votre eSIM peut y faire, et pour la plupart des eSIM de voyage la réponse est rien : un accord de gros par pays, un réseau, et aucune issue sauf acheter une deuxième eSIM chez quelqu'un d'autre, debout dans la rue.

Ici le trafic Orbislo passe par KDDI et SoftBank. Quand le réseau où vous êtes se dégrade, nous vous basculons sur un autre, en plein voyage, sans que vous demandiez, et nous vous le disons après plutôt que de vous interrompre sur le moment.

Les opérateurs mobiles en Japon

• NTT Docomo: NTT Docomo held 32.9 percent of Japan's mobile contracts at the end of March 2026 on the ministry's count, rising to 39.5 percent once lines it supplies wholesale to virtual operators are included, making it the largest of the four licensed networks.
• KDDI: The KDDI group held 26.2 percent of mobile contracts at the end of March 2026, or 31.4 percent including the lines it supplies to virtual operators.
• SoftBank: SoftBank held 18.7 percent of Japan's mobile contracts at the end of March 2026, or 24.6 percent including the lines it supplies to virtual operators, according to the communications ministry's quarterly figures.
• Rakuten Mobile: Rakuten Mobile held 3.6 percent of mobile contracts as a network operator at the end of March 2026. Virtual operators running on the other networks together held 18.5 percent.
• Rakuten Mobile, 700 MHz: In October 2023 the ministry approved Rakuten Mobile's plan to build base stations in the 770 to 773 MHz block. Rakuten was the only applicant for that 700 MHz band spectrum, which was assigned with conditions attached.

Les anciens réseaux en Japon

• KDDI and Okinawa Cellular switched off au's 3G service, CDMA 1X WIN, on 31 March 2022, after running it since November 2003. From 1 April 2022 au handsets that could not make VoLTE calls stopped working.
• SoftBank ended its 3G service on 15 April 2024, having postponed the January date after the Noto Peninsula earthquake. Customers living in Ishikawa Prefecture kept 3G inside that prefecture until 31 July 2024.
• NTT Docomo closed its FOMA 3G network and the i-mode service on 31 March 2026. Since then a phone that cannot make VoLTE calls, or has VoLTE switched off in its settings, cannot make voice calls on Docomo at all.

La 5G en Japon

• In April 2019 Japan assigned its first 5G spectrum to four operators: NTT Docomo and KDDI with Okinawa Cellular received two 100 MHz blocks each between 3.6 and 4.6 GHz, SoftBank and Rakuten Mobile one each, and every operator also received a 400 MHz block between 27.0 and 29.5 GHz.
• In December 2024 the ministry approved SoftBank's plan for the 4.9 to 5.0 GHz band, the only application it received, adding a further 100 MHz of 5G spectrum to SoftBank's network.
• At the end of March 2025, 5G reached 98.4 percent of Japan's population when the four operators' coverage is combined, and between 88.4 and 99.9 percent in each prefecture. The government's target is 99 percent nationally and in every prefecture by March 2031.
• By the end of March 2026 Japan counted 126.32 million 5G contracts, up 12.7 percent in a year, against 108.85 million 4G contracts, so 5G lines now outnumber 4G ones.

Le réseau en Japon : à savoir

• Since 1 April 2026 the four network operators run JAPAN Roaming: when a disaster or major outage knocks out one network, its customers can switch to another at up to 300 kbps, or in some cases make emergency calls only. The phone shows a network name such as JPN-ROAM D, K, S or R.
• JAPAN Roaming is switched on only for large scale disasters or major network failures, not for everyday or small outages. Smartphones from roughly the spring 2026 models onward are expected to support it, and some older models gain support through software updates.
• The January 2024 Noto Peninsula earthquake took up to 839 mobile base stations off air across the four networks, 799 of them in Ishikawa Prefecture, as power cuts and severed transmission lines spread. KDDI, SoftBank and Rakuten Mobile finished emergency restoration on 15 January and Docomo on 17 January, except where landslides blocked access.