Going to a crowded festival without losing each other: a communication guide when the network is congested

This scene is familiar to anyone who has ever gone to hanabi: you split from the group to buy food, turn back and see no one, open your phone to call—it doesn't ring. You message—the circle keeps spinning. You open the map—it's blank. Meanwhile, you're surrounded by tens of thousands of people who look identical in the dark.

This article explains why that happens (it's not your carrier's fault), and more importantly: the exact protocol to ensure your group never falls into that situation.

1. Why does the network get congested at festivals? An easy-to-understand explanation

Imagine a cell tower as a road. On normal days, that area has 5,000 people, so the road is wide open. On festival night, 300,000 people are standing there together—yet the road is still the same width. The result is a traffic jam.

More specifically, each cell tower can only handle a certain number of simultaneous connections. When that threshold is exceeded:

• Voice calls are blocked first (they consume the most resources)—you hear "currently unable to connect."
• Videos and photo uploads practically grind to a halt.
• Text messages usually still "slip through" because their data packets are very small—this is the key point you need to remember.

Important: this is a physical phenomenon that happens with every carrier—Docomo, au, SoftBank, or budget SIMs are all the same. Changing carriers won't solve it. What solves it is how you prepare.

2. A 5-step protocol before leaving the house

Step 1: Agree on a "rescue meeting point"

Before going, the whole group agrees on a specific location + a specific time. Principles for choosing:

• Absolute specificity: "The 7-Eleven store north of bridge X"—not "near the bridge" or "by the food stalls."
• Choose something stationary with a name: a combini, a specific station exit number, a monument, a numbered light pole.
• Avoid overly crowded places like the main station exit—where you couldn't find each other even if you stood right there.
• Have two time milestones: one right after the event ends (e.g., 21:15) and a backup 30 minutes later (21:45).

Step 2: Screenshot everything important

Area maps, tickets, seat numbers, return train schedules (including the last train), hotel addresses. Screenshots can be viewed even during a total network blackout.

Step 3: Download offline maps

Google Maps → search area → menu → "Download offline map." After that, navigation still works without a network because GPS doesn't need the internet.

Step 4: Fully charge + bring a portable charger

A little-known tip: when the signal is weak, your phone increases its transmission power to try and catch a signal—this is why the battery drops unusually fast at festivals. Turn on battery saver mode right from the start of the evening.

Step 5: Take a group photo at the beginning

It sounds strange but it's extremely useful: if you have to ask staff or police to find someone, you instantly have a photo of what they're wearing today. For young children, this is mandatory.

3. Once you are at the festival

1. Remember landmarks around your seat: light pole number, stall name, tree type. Take a photo of your seating area looking outwards.
2. Go to the restroom and buy things in pairs, never go alone—especially children and the elderly.
3. Text instead of calling when you need to communicate: short messages are much easier to "slip through."
4. Message before leaving your spot: "I'm going to buy takoyaki, back in 10 minutes"—so the group doesn't panic.
5. Reschedule if plans change, don't leave people guessing.

4. What to do if you actually get lost?

In the first 5 minutes

• Stand still in one place for 2–3 minutes. If both of you wander off looking for each other, it's even harder to meet. Whoever still remembers the old spot should return to it.
• Send a short message (no photos, no video calls): "I'm near the ice cream cart, standing still here."
• If possible, turn on location sharing—but don't rely on it entirely, as this feature requires a network.

If you cannot make contact

• Go to the agreed meeting point and wait until the backup time milestone. This is when preparation step 1 pays off.
• Find a high spot or bright spot to make it easier to spot each other.
• Head toward the edge of the crowd—where there are fewer people, the signal is also better, and you might even be able to make a call.

If a child gets lost

1. Immediately report it to event staff (uniforms with logos, usually standing along walkways) or police. Don't be shy because of language barriers—just say "kodomo ga imasen" (my child is missing) and show the photo.
2. Most large festivals have a lost children center (迷子センター)—ask the nearest staff member.
3. Before leaving, write your name + phone number on a small piece of paper in their pocket, and tell the child: "If you get lost, find someone wearing a badge or a vendor, and give them this paper."

5. Six battery-saving tips for festival night

1. Turn on battery saver mode right when leaving the house.
2. Lower screen brightness—it's night time, 40% brightness is plenty.
3. Turn off automatic photo cloud backup over mobile data.
4. Turn off WiFi and Bluetooth if not in use—constantly scanning drains a lot of battery.
5. Don't "fight" the network: when you see something loading endlessly, stop. The more you try, the more battery and data you waste.
6. Turn on airplane mode when not needed (for example, while watching), then turn it off when you need to communicate—the most powerful battery-saving method.

6. Special case: going with the elderly

• Choose a medium-scale festival instead of one with a million people.
• Choose seating close to the exit and near the restroom.
• Plan ahead to leave 10 minutes early before the finale to avoid the crowds.
• Write your phone number on a piece of paper kept in their wallet.
• Prepare water, a small folding chair if possible, and watch for signs of heatstroke.

7. What about data consumption?

Festival night is the biggest data-guzzling night of the year for many people: recording videos, posting stories, video-calling family to watch live. Three figures for you to visualize:

• Recording 1080p video: about 130MB per minute (if automatic cloud backup over mobile data is enabled).
• Video calling: about 200–350MB per hour.
• Posting a story with video: 20–60MB.

Combined, an enthusiastic night of "virtual living" can consume 2–4GB. If your plan is 10GB/month, one night will wipe out a third of it. How to handle it: turn off automatic backups, post when you get home with WiFi, and check your remaining data before leaving.

If you plan to visit several festivals this summer and find that your current plan runs out too early, send HD TELECOM a screenshot of your data usage statistics along with your plan name—we will gladly review it for free in Vietnamese to help you decide whether to keep it, top up, or switch plans to suit your needs.

Quick cheat sheet — screenshot this before you go

Conclusion

No technical trick can beat physics: when hundreds of thousands of people stand in one place, the network will congest. But there is one thing that always works even if the network completely crashes—a meeting point and a time milestone agreed upon in advance. Thirty seconds of discussion before leaving the house trades for peace of mind all evening. Wishing you and your family a fulfilling Japanese summer night 🎆