About

denntatsu

denntatsu is a direct peer-to-peer voice push-to-talk app that connects nearby devices over Bluetooth and Wi-Fi, without going through a server. It is built as a companion for outdoor activities such as motorcycle touring, hiking, and survival games in areas with no cell signal, and also provides free, unlimited disaster SOS and safety check-in features for use when cellular infrastructure is down.

Why denntatsu

Once you're out of cell signal, a smartphone becomes just a clock. denntatsu is built for people who ride, hike, or play survival games together in fields with no cell coverage: it connects devices directly over Bluetooth and Wi-Fi, without going through a carrier's base station.

What it does

Works with no signal: nearby devices connect directly over Bluetooth and Wi-Fi — no server, no mobile network required.
Push-to-talk, walkie-talkie style: press and hold to transmit voice, with text chat available alongside it.
Connect with a QR code: scan a channel's QR code for offline pairing.
Free, unlimited disaster SOS: when infrastructure is down, nearby devices relay SOS and safety-check messages to each other over repeated P2P connections. This is not a substitute for official emergency numbers (110/119 in Japan) and does not guarantee delivery.

Why we built it

The primary use case is as a substitute for voice intercoms on motorcycle tours, hikes, and survival games in areas with no cell signal. The disaster SOS and safety check-in features grew out of the idea that the same peacetime P2P communication layer can be repurposed during a disaster — we provide them free and unlimited as well.

How it works

denntatsu uses two communication layers: a Bluetooth control layer that stays connected to discover nearby devices and coordinate sessions, and a Wi-Fi data layer that carries the actual voice audio while the app is in the foreground. Devices can also relay messages for each other, extending reach beyond a single hop when your group is spread out on the move.

About Us

Name: En-Links LLC (合同会社エン・リンクス)
Representative: Seita Aoki
Address: 1-11-3F Funatsu-cho, Kagoshima City, Kagoshima Prefecture, Japan
Contact: support@denntatsu.com