SoftBank Corp network coverage across Japan as of 2026

SoftBank Corp Review: Coverage & Performance In Japan 2026

SoftBank Corp delivers 98.4% 5G population coverage across Japan's 47 prefectures, leads all national carriers with a median download speed of 62.05 Mbps, and serves 40.48 million mobile subscribers as of FY2025. This review covers network performance, customer service, key features, and how SoftBank compares against NTT Docomo and KDDI au.

Introduction

Japan's third-largest wireless carrier SoftBank Corp. (Tokyo Stock Exchange: 9434) operates as a full-service telecommunications operator headquartered in Minato, Tokyo, delivering mobile, fixed-line broadband, and enterprise ICT services to 40.48 million mobile subscribers and capturing approximately 25.9% of Japan's mobile subscription market as of March 2024, according to Statista Market Data published June 2024.

SoftBank Corp. ranks as Japan's fastest mobile network overall in 2025, recording a median download speed of 62.05 Mbps across all network types — ahead of KDDI au at 57.85 Mbps, Rakuten Mobile at 53.54 Mbps, and NTT Docomo at 50.50 Mbps, according to Speedtest Intelligence data from Ookla Q3 2025. The carrier's 5G network reaches 98.4% of Japan's population, placing it within a national coverage tier shared by all four major operators.

This review examines SoftBank's 4G and 5G network coverage by prefecture, speed test results across Tokyo, Osaka, and Nagoya, customer service channels and satisfaction ratings, value-added features including international roaming across 170-plus countries, eSIM availability, and a head-to-head comparison with competitors NTT Docomo and KDDI au. The review draws exclusively on data from Ookla Speedtest Intelligence, Japan's Ministry of Internal Affairs and Communications (MIC), SoftBank Corp. financial disclosures, and J.D. Power Japan.

Compare NTT Docomo's full carrier review and the KDDI au review for additional mobile carrier options in Japan.

Network Coverage And Performance

SoftBank Corp. covers 98.4% of Japan's population with 5G service across all 47 prefectures. Japan's Ministry of Internal Affairs and Communications confirmed this figure in its 5G Development Status report published September 2025, reflecting measurements as of the end of fiscal year 2024 (March 31, 2025). Per-prefecture 5G coverage ranges from 88.4% to 99.9%, with the highest density concentrated in metropolitan areas including Tokyo, Osaka, and Nagoya.

4G LTE availability across all Japanese operators — including SoftBank — consistently exceeds 97% nationally, according to Ookla Speedtest Intelligence Q3 2025. SoftBank operates LTE on Bands 1 (2,100 MHz), 3 (1,800 MHz), 8 (900 MHz), 11 (1,500 MHz), and 28 (700 MHz), and deploys 5G on the 3.7 GHz and 28 GHz (millimeter wave) spectrum bands. The carrier and KDDI are jointly constructing 100,000 5G base stations each by 2031, according to Asian Telecom Industry Report published November 2025.

4G And 5G Availability

SoftBank's 5G availability score — the share of time 5G-capable device users connect to a live 5G signal — stands at 26.5% nationally as of Q3 2025. This is the lowest among Japan's four major operators in this specific metric, behind NTT Docomo at 38.4% and KDDI au, according to Speedtest Intelligence data published by Telecomstechnews in December 2025. Geographic availability varies significantly: Osaka prefecture records 35.2% 5G availability, while Yamanashi prefecture records 9.1%.

Despite lower availability scores, SoftBank records the highest 5G consistency scores in many regions, particularly Hokkaido and the Tōhoku region, reflecting reliable sustained performance where 5G connections are established, according to the same Ookla report. SoftBank's 5G median download speed reaches 127.45 Mbps with upload speeds of 17.51 Mbps, placing it second nationally in 5G speed behind Rakuten Mobile's 128.39 Mbps.

Speed Test Results

SoftBank delivers a median download speed of 62.05 Mbps and an upload speed measured across all network types, ranking first among Japan's four national carriers, according to Speedtest Intelligence data from Ookla Q3 2025. In the Chubu region — covering prefectures including Aichi, Nagano, and Niigata — SoftBank recorded an average 5G download speed of 178.7 Mbps across 140 test locations, according to Telecompaper published October 2025.

Learn more about 5G network performance in Japan for detailed technical comparisons across all four national operators.

Company Information And Market Position

SoftBank Corp. was established in 2004 as the mobile operator entity within SoftBank Group Corp. (Tokyo Stock Exchange: 9984), Japan's diversified technology conglomerate. The carrier trades independently on the Tokyo Stock Exchange under ticker 9434 and reported record revenue of JPY 3,400.8 billion for Q2 FY2025 — an 8% year-over-year increase — according to the SoftBank Corp. Q2 FY2025 earnings transcript published November 2025. SoftBank Group Corp. remains the parent company.

SoftBank Corp. held 25.9% of Japan's mobile subscription market as of March 2024, placing it third among the four national operators behind NTT Docomo and KDDI, according to Statista Market Data published June 2024. The carrier reported a cumulative subscriber base of 40.48 million mobile main subscribers as of FY2025, according to SoftBank Corp. Integrated Report 2025 Data Section. The Consumer Business segment — SoftBank's largest division — generated JPY 2,253.2 billion in revenue during FY2025 Q1–Q3, a 3% year-over-year increase, according to SoftBank Corp. Q3 FY2025 earnings report published February 2026.

Customer Service And Support

SoftBank Corp. operates 6,400 retail stores nationwide alongside multiple digital support channels including phone, in-app chat, and web support. Y!mobile — SoftBank's value sub-brand — ranked No. 1 in the J.D. Power 2024 Japan Mobile Phone Service Customer Satisfaction Survey in the value carrier category for three consecutive years, achieving top scores across the four factors of Communication Quality, Service Menu, Provided Devices, and Procedure or Support Response, according to SoftBank Corp. External Evaluations page updated 2024. The main SoftBank brand also ranked No. 1 overall in the 2022 JCSI (Japanese Customer Satisfaction Index) Survey for the cell phone industry.

• >Phone Support: Available via the SoftBank customer service line at 157 (from SoftBank handsets) or +81-92-687-0025 (from other phones or overseas) — operating hours 9:00 AM–8:00 PM JST daily. >Physical Stores: 6,400 SoftBank shop locations across Japan's 47 prefectures, including flagship English-language service stores in Tokyo (Ginza, 5-7-8 Chuo-ku, open 10:00 AM–8:00 PM), Osaka, and Nagoya, according to the SoftBank Shop official page. >Video Call Support: English-speaking customer service available via video call at designated direct stores, with advance reservation required, according to SoftBank Shop official page. >Mobile App (My SoftBank): Provides in-app chat and account ticket submission; the app received the 2021 Good Design Award and is available on iOS and Android, according to Google Play listing updated August 2025. >Web Chat and Online Portal: Available through My SoftBank web portal for account management, bill payment, and plan changes.

Compare customer service options across Japan's carriers in our comprehensive Japan carrier support comparison guide.

Additional Services And Features

SoftBank Corp. provides these value-added services for subscribers:

• > International Roaming: SoftBank's "Worry-free Global Roaming Flat Rate" service covers 99% of popular overseas travel destinations across regions including Europe, Asia, North America, and Oceania, according to the SoftBank Global Roaming official page. The plan provides up to 3 GB of flat-rate data for category L countries. > Mobile App Features (My SoftBank): The My SoftBank app delivers data usage monitoring, bill viewing and payment, plan change and upgrade management, customer support chat and ticket submission, store locator with reserve-a-visit functionality, and rewards program tracking — a total of 6 core functions available on iOS and Android. > eSIM Support: SoftBank supports eSIM activation for compatible iPhone and Android devices, enabling remote SIM provisioning without a physical SIM card. The carrier also offers prepaid travel eSIM products for inbound visitors to Japan, providing 4G LTE coverage for stays from 3 to 30 days, according to eSIM Japan user guide published November 2024. > Rewards And Loyalty Program (PayPay Points): SoftBank subscribers earn PayPay Points on monthly billing, which redeem across PayPay's payment ecosystem covering millions of merchants in Japan, including Yahoo! Shopping, PayPay Mall, and physical retail partners. Yahoo! JAPAN — a SoftBank Group affiliate — records an average of 81 million monthly users, according to SoftBank Corp. Integrated Report 2025. > 5G Device Support: SoftBank supports a full range of 5G-compatible smartphones from Apple (iPhone 16 series), Samsung (Galaxy S25 series), and Sony (Xperia 1 VII), along with SoftBank-branded AQUOS devices operating on both Sub-6 GHz (3.7 GHz) and millimeter wave (28 GHz) 5G bands. > Family Plans And Shared Data: SoftBank's "Merihari Plan" family option provides shared data pools and discounted additional lines, with per-line savings applicable from the second line onward.

Discover more about eSIM activation in Japan for a step-by-step guide to setting up eSIM on compatible devices.

SoftBank Corp Pros And Cons

Advantages

• > Fastest Overall Mobile Network In Japan: SoftBank records the highest median download speed of 62.05 Mbps across all network types in Q3 2025, ahead of KDDI au (57.85 Mbps), Rakuten Mobile (53.54 Mbps), and NTT Docomo (50.50 Mbps), according to Ookla Speedtest Intelligence Q3 2025. > Near-Universal 5G Population Coverage: SoftBank's 5G network reaches 98.4% of Japan's population across all 47 prefectures as of March 2025, matching the national coverage tier of Japan's major operators, according to Japan's Ministry of Internal Affairs and Communications report published September 2025. > Highest 5G Consistency In Key Regions: SoftBank records the highest 5G consistency scores in Hokkaido and Tōhoku, enabling stable video streaming and low-latency applications in those regions, according to Ookla Speedtest Intelligence Q3 2025. > Top-Ranked Customer Satisfaction (Value Brand): Y!mobile, SoftBank's sub-brand, ranked No. 1 in J.D. Power Japan's 2024 Mobile Phone Service Customer Satisfaction Survey (value carrier category) for three consecutive years, according to SoftBank Corp. External Evaluations published 2024. > Extensive Retail Presence: 6,400 SoftBank shops nationwide provide in-person support across all 47 prefectures, including English-speaking staff at flagship locations in Tokyo Ginza, Osaka, and Nagoya, according to SoftBank Shop official page.

Disadvantages

• > Lowest 5G Availability Score Among Major Operators: SoftBank's 5G availability rate of 26.5% — measuring actual 5G connection time for 5G-capable device users — is the lowest of Japan's four major carriers, more than 11 percentage points below NTT Docomo's 38.4%, according to Ookla Speedtest Intelligence Q3 2025. > Inconsistent 5G Performance In Rural Prefectures: SoftBank's 10th-percentile 5G download speed drops to 4 Mbps in Nagano and 6 Mbps in Chiba — among the lowest recorded by any major operator in those prefectures — indicating significant rural network congestion or coverage gaps, according to Ookla Speedtest Intelligence Q3 2025. > My SoftBank App Language Limitation: The My SoftBank app is primarily in Japanese, with limited English-language navigation, drawing repeated complaints from foreign-resident users in Google Play reviews updated August 2025, reducing accessibility for non-Japanese speakers. > International Roaming Data Caps: SoftBank's flat-rate roaming plan provides only 3 GB of data per trip in category L countries, which limits heavy data users traveling abroad and may require additional top-ups, according to SoftBank Global Roaming official page.

SoftBank Vs Competitors

Japan's mobile market comprises four national operators — SoftBank Corp., NTT Docomo, KDDI au, and Rakuten Mobile — competing across speed, 5G deployment, subscriber base, and customer experience. SoftBank differentiates through the highest overall network speeds, the broadest retail footprint, and deep integration with the Yahoo! JAPAN and PayPay digital ecosystems. NTT Docomo leads in 5G availability and subscriber count, while Rakuten Mobile leads in 5G download speeds and offers the most disruptive low-cost positioning.

SoftBank Corp vs NTT Docomo vs KDDI au — key performance metrics comparison 2025

SoftBank is the best choice for users who prioritize raw download speed and gaming performance — the carrier recorded the top mobile gaming score (Game Score 82.94) in Japan during H1 2024, according to Ookla Speedtest Connectivity Report Japan H1 2024 published August 2024. NTT Docomo is better suited for users who need the widest 5G connection time and the largest network by subscribers. Rakuten Mobile delivers the fastest 5G peak speeds at the lowest price points for budget-conscious users.

Read the detailed SoftBank vs NTT Docomo comparison or explore the Rakuten Mobile full review for alternative options in Japan.

Frequently Asked Questions About SoftBank Corp

Does SoftBank Corp Have 5G Coverage In Japan?

SoftBank Corp's 5G network covers 98.4% of Japan's population across all 47 prefectures as of the end of fiscal year 2024. Per-prefecture coverage ranges from 88.4% in less urbanized areas to 99.9% in dense metropolitan prefectures including Tokyo, Osaka, and Aichi. Japan's Ministry of Internal Affairs and Communications confirmed these figures in the 5G Development Status report published September 2025. SoftBank and KDDI are jointly deploying 100,000 5G base stations each by 2031 to close remaining rural gaps.

How Fast Is SoftBank Corp's Mobile Internet Speed?

SoftBank delivers Japan's fastest median download speed of 62.05 Mbps across all network types as of Q3 2025. On 5G specifically, SoftBank records a median download speed of 127.45 Mbps and upload speed of 17.51 Mbps, ranking second nationally behind Rakuten Mobile's 128.39 Mbps. In the Chubu region — covering Aichi, Nagano, and Niigata — SoftBank achieved an average 5G download speed of 178.7 Mbps across 140 test locations, according to Ookla data published by Telecompaper in October 2025.

What Areas Does SoftBank Corp Cover In Japan?

SoftBank covers all 47 of Japan's prefectures with both 4G LTE and 5G service, reaching 98.4% of the national population. Coverage is strongest in Tokyo, Osaka, Nagoya, Fukuoka, and Sapporo metropolitan areas. Rural prefectures including Yamanashi record lower 5G availability at 9.1%, while urban prefectures like Osaka reach 35.2% 5G availability, according to Ookla Speedtest Intelligence Q3 2025. 4G LTE availability across Japan exceeds 97% in all regions.

How Do I Contact SoftBank Corp Customer Service?

SoftBank Corp. customer service is reachable by dialing 157 from a SoftBank handset or +81-92-687-0025 from any phone, available 9:00 AM–8:00 PM JST daily. In-person support is available at 6,400 SoftBank shops across Japan, including English-speaking staff at flagship stores in Tokyo Ginza (5-7-8 Chuo-ku, open 10:00 AM–8:00 PM), Osaka, and Nagoya. Customers can also contact support through the My SoftBank app's in-app chat or via video call reservation at designated direct stores, according to the SoftBank Shop official page.

Does SoftBank Corp Support eSIM?

SoftBank Corp. supports eSIM activation for compatible iPhone and Android smartphones, allowing digital SIM provisioning without a physical card. For inbound visitors, SoftBank-network travel eSIM products provide 4G LTE data coverage in Japan for durations ranging from 3 to 30 days. These travel eSIMs are single-use and designed for Japan-only use; they cannot be recharged once activated, according to eSIM Japan user guide published November 2024.

What Countries Does SoftBank Corp Roaming Cover?

SoftBank's "Worry-free Global Roaming Flat Rate" covers 99% of popular overseas travel destinations, spanning regions including Europe, Asia, North America, South America, and Oceania. The flat-rate plan allocates up to 3 GB of roaming data in category L countries; once exhausted, data continues at reduced speeds. Voice calls, video calls, and overseas SMS messages are not included in the flat-rate plan and are charged separately, according to the SoftBank Global Roaming official service page.

How Does SoftBank Corp Compare To NTT Docomo?

SoftBank leads NTT Docomo in overall median download speed (62.05 Mbps vs 50.50 Mbps) and 5G download speed (127.45 Mbps vs 112.12 Mbps), but trails in 5G availability (26.5% vs 38.4%) and total subscribers (40.48 million vs approximately 88 million). SoftBank operates 6,400 retail stores versus NTT Docomo's approximately 2,300 Docomo shops, providing significantly broader in-person service access. For users prioritizing consistent 5G connectivity time, NTT Docomo is the stronger choice; for raw speed performance, SoftBank leads, according to Ookla Speedtest Intelligence Q3 2025.

What Is The Best SoftBank Corp Feature?

SoftBank's best-in-class feature is its fastest overall mobile network speed in Japan, with a median download of 62.05 Mbps across all network types as of Q3 2025. This extends to gaming performance: SoftBank recorded Japan's highest mobile Game Score of 82.94 and best 5G Game Score of 87.31 during H1 2024, according to Ookla Speedtest Connectivity Report Japan H1 2024 published August 2024. The PayPay Points rewards integration — spanning millions of merchants and Yahoo! JAPAN's 81 million monthly users — ranks as the most comprehensive loyalty ecosystem among Japan's four major operators.

Conclusion

SoftBank Corp. is Japan's fastest mobile network in 2026, delivering 62.05 Mbps median speeds, 98.4% 5G coverage, and 6,400 retail stores — the strongest choice for speed-focused users and gamers in Japan.

Explore more mobile carrier options through our complete Japan carrier directory or learn how to choose the right carrier for your needs in Japan.

Last Updated: March 18, 2026

Sources:

1. > Telecomstechnews / Ookla Speedtest Intelligence — Japan 5G Network Performance Q3 2025, December 2025 > Ookla Speedtest — Japan Connectivity Report H1 2024, August 2024 > Japan Ministry of Internal Affairs and Communications (MIC) — 5G Development Status FY2024, September 2025 > Statista — SoftBank Mobile Phone Subscription Market Share Japan 2015–2024, June 2024 > Telecompaper — SoftBank Fastest 5G Download Speeds in Japan's Chubu Region, October 2025 > SoftBank Corp. Integrated Report 2025 > SoftBank Corp. Official Website — softbank.jp

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