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IIJmio vs ahamo vs povo Speed Test 2026: Which is Fastest?

Speed comparison of IIJmio, ahamo, and povo in Japan 2026. ahamo and povo run directly on Docomo/au networks with no throttling. IIJmio is an MVNO—faster off-peak, slower at lunch and evening. MMD Research March 2026 ranked povo #1.

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Last verified: March 13, 2026 (JST)

As of March 2026, ahamo and povo rank #1 in independent speed studies, while IIJmio trades lower peak-hour speeds for significantly cheaper monthly pricing. This guide explains exactly why—and helps you decide which plan fits your actual usage patterns.

The Key Difference: Sub-Brands vs. MVNOs

To understand speed differences between these three carriers, you need to understand how they access Japan's mobile networks.

ahamo and povo: Direct Sub-Brand Access

ahamo (NTT Docomo sub-brand) and povo (KDDI/au sub-brand) are not MVNOs—they are online-only brands that operate directly on their parent carrier's network infrastructure. This means:

  • Full priority access to Docomo (ahamo) or au (povo) network capacity
  • No deprioritization behind "premium" carrier customers
  • Consistent fast speeds throughout the day, including peak congestion hours
  • The same data transmission routes as a full-price Docomo or au contract

When you use ahamo or povo, your data traffic is treated identically to a ¥7,000/month Docomo or au plan holder. The "budget" aspect only applies to the price—the network performance is identical.

IIJmio: MVNO Using Shared Bandwidth

IIJmio is an MVNO (Mobile Virtual Network Operator) that leases bandwidth from NTT Docomo and au rather than owning its own network. IIJmio purchases a set amount of network capacity and shares it across all its customers. This model enables low prices (from ¥850/month) but creates a fundamental speed trade-off:

  • During off-peak hours (late night, early morning, mid-morning), IIJmio speeds are excellent and often match sub-brand performance
  • During peak hours (lunch 12:00–13:00, evening commute 19:00–21:00, weekends), network congestion slows IIJmio speeds noticeably as shared capacity fills up
  • IIJmio has invested in network capacity and performs better than many MVNOs, but cannot fully eliminate peak-hour slowdowns inherent to the shared bandwidth model

Speed Rankings: What the Research Shows

MMD Research March 2026 Ranking

MMD研究所 (MMD Laboratory), a leading Japanese mobile research firm, published a 9-carrier communication speed ranking in March 2026 (reported on ITmedia Mobile). Key findings:

  • povo ranked #1 in the overall speed ranking among the 9 carriers tested
  • Sub-brands (ahamo, povo) consistently outperformed MVNOs in peak-hour testing
  • MVNO performance varied significantly between peak and off-peak measurement periods

For the full dataset and methodology, visit mmdlabo.jp for the complete March 2026 report.

Why povo Ranked #1

povo runs on KDDI/au's network, which has undergone significant capacity upgrades in recent years. Because povo users receive the same network priority as full-price au customers, they benefit from these improvements without congestion penalties. The ¥0 base rate model (with paid data toppings) also means lower average usage per subscriber compared to flat-rate carriers, potentially reducing network load during peak hours.

ahamo's Performance

ahamo performs comparably to povo in most speed tests. Docomo's network is Japan's most extensive by coverage, which makes ahamo particularly strong in rural areas and inside buildings. Docomo has historically led in building penetration and underground subway coverage—advantages that directly benefit ahamo users. In urban core areas, the speed difference between ahamo and povo is minimal in everyday usage.

Practical Speed Comparison

Carrier Network Type Peak-Hour Speeds Off-Peak Speeds Congestion Risk
povo Sub-brand (au) Excellent Excellent Very low
ahamo Sub-brand (Docomo) Excellent Excellent Very low
IIJmio MVNO (Docomo/au) Moderate Good–Excellent Moderate

What "peak-hour speeds" means in practice:

  • Excellent: Pages load instantly, 4K video streams without buffering, video calls are smooth
  • Good: Normal browsing and streaming work well, very occasional brief pauses
  • Moderate: Pages may take 3–8 seconds to load, HD video may buffer occasionally, noticeable during 12–13:00 and 19–21:00

Price Comparison: Speed Costs More

Carrier Monthly Price Data Network
IIJmio (voice SIM) ¥850 (2GB) 2GB Docomo
povo ¥0 base + toppings Pay-per-use au
ahamo ¥2,970 30GB Docomo

IIJmio's ¥850/month for 2GB voice SIM is remarkable value—it's more than 3x cheaper than ahamo for light data users who can tolerate peak-hour slowdowns. povo's ¥0 base offers theoretical zero cost but requires purchasing data toppings (e.g., 3GB for ¥990 valid 30 days, or 20GB for ¥2,728 valid 30 days).

When to Choose Each Carrier

Choose povo if:

  • Speed consistency is your top priority
  • Your usage is variable month to month (some months light, some heavy)
  • You're comfortable managing data topup purchases
  • You don't need continuous monthly data—povo lets you go without data in low-usage months

Choose ahamo if:

  • You want a simple fixed monthly fee with 30GB of data
  • You travel internationally 2+ times per year (30GB free roaming in 91 countries is exceptional)
  • You need strong rural coverage (Docomo's network is widest nationally)
  • You use 20–30GB consistently each month

Choose IIJmio if:

  • Budget is your primary concern—¥850/month for 2GB is hard to beat
  • You primarily use WiFi and only need mobile data occasionally
  • You use your phone mostly during off-peak hours (not during lunch or evening commute)
  • You're comfortable with occasional slower speeds during peak periods

Real-World Usage Considerations

For Students

University students often fit IIJmio's usage pattern: WiFi on campus and at home, mobile data mainly for commuting and occasional use. If you're on campus or home WiFi most of the day and only need data for maps, social media, and messaging during commutes, IIJmio's ¥850–¥1,500/month plans offer excellent value despite peak-hour limitations.

For Remote Workers

If you rely on mobile data for video calls, cloud file access, or client communication during business hours—particularly around noon—the MVNO congestion risk makes ahamo or povo worth the premium. A dropped video call or slow file upload during a client meeting costs more than the monthly price difference.

For International Travelers

ahamo is the clear winner for frequent travelers: 30GB of free international data in 91 countries is unmatched among budget carriers. povo and IIJmio charge for international roaming. If you take 2+ international trips per year, ahamo's roaming benefit alone can justify the higher monthly cost.

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