Hundreds of people have stood in long lines outside Japanese stores to buy the Pokemon GO Plus device.
In Osaka City, around 700 people waited outside a Pokemon Centre shop to buy the device when the store opened at 8 am, two hours earlier than usual.
Pokemon GO Plus allows Pokemon GO players to interact with the mobile game without looking at the phone.
"(Using the peripheral gear), Pokemon hunting will speed up because I don't have to stare at the (Smartphone) screen. I want to get them (Pokemon monsters) one after another," said Kana Sugiura, 29, who was waiting outside the store, to Japanese news agency Kyodo.
Pokemon GO Plus is a gadget similar to a wristwatch but attached with a clip that connects to the game.
The device, which costs around $US35 ($A47), is connected to the mobile phone via Bluetooth, and through a led light (green or blue) and vibrations notify the player when there is a 'poke stop' or a Pokemon nearby, which can then be captured by pressing the device button without any need for the phone.
The peripheral add-on is available from Friday in most countries - including Australia, said game developer Niantic in a statement.
