This article is about a/an communication device and Rider Machine in Kamen Rider Build.
Build Phone

Build Phone (Phone Mode)

"Build Change!"
―Transformation announcement from Phone Mode to Bike Mode[src]

The Bike Transforming Build Phone (バイク変形ビルドフォン Baiku Henkei Birudo Fon) is Kamen Rider Build's personal smartphone and one of his inventions.[1] It can also transform into the Machine Builder Rider Machine by utilizing the Lion Fullbottle. The Machine Builder is shared with Kamen Rider Cross-Z [2].


The Build Phone, like regular smartphones, is equipped with mobile apps.

  • Helmet: This app appears when the BuildPhone is in its vehicle mode. When activated, a motorcycle helmet will materialize for Sento or a passenger rider to wear.
  • Mail: An Email app. Usually used to read messages sent to the phone and announces a message has come with the retro phrase "You've got mail!".

Machine Builder

Machine Builder
Machine Builder
Rider: Kamen Rider Build
Kamen Rider Cross-Z
Series: Kamen Rider Build
Length: 214[3] cm
Weight: 134 kg
Speed: 271 km/h
Base Model: Honda XR 230

The Machine Builder (マシンビルダー Mashin Birudā) is the vehicle mode of the Build Phone.[4]

  • Total Power/Horsepower: 104.4 kw/140 HP

The Machine Builder is equipped with GPS navigation and is equipped with High Balancer Tires (ハイバランサータイヤ Hai Baransā Taiyasu) that have a multi-directional air injection system. This allows the bike to remain perfectly balanced and at full speed can run up and down slopes, the sides of buildings or the Sky Wall. The Front Gear Light (フロントギアライト Furonto Gia Raito) on the handle bars is equipped a high beam headlight along with thermal and infrared sensors to see enemies in the dark or in hidden areas. The Front Gear Light can also extend outward for combat use, rotating at high speed like a buzzsaw and using an unnamed Rider Break attack to ram right through objects or a large enemy such as the Guardian Union State mechas. The Guard Red Cowl covering the bike is made from a special armor material that is super durable and protects the internal components of the bike from damage, able to withstand any attack by a Smash. The Machine Builder's seat cushion is automatically adjustable to provide its occupants with a comfortable ride and adjusts to negate some of the force of impact from rougher travel on uneven terrain, during a battle or from high jumps.

The Rear Bottle Charger (リアボトルチャージャー Ria Botoru Chājā) draws power from the enlarged Lion Full Bottle to maximize output allowing the bike to achieve explosive bursts of speed. It can also create a saw blade energy construct by Build going at full speed and executing a wheelie. The front tire then begins to glow in a golden aura that transforms into a saw blade to slice obstacles or targets. Technology of Destruction

The handlebars and throttle have a computer system that allows the Machine Builder to read the user's driving ability and habits, then optimizes performance to better be utilized by whomever is driving it. The bike can also use its phone apps for various functions, including a cell phone, radar and materializing helmets for the driver and a passenger to wear using a built in touch screen display.

Appearances: Build Episodes 1-7, 10, 12, Heisei Generations FINAL: Build & Ex-Aid with Legend Riders



  • This marks the first time since Gaim that a Rider Machine is stored/concealed in a portable device.
    • Both Rider Machines require the use of the series collectible to summon them, however this marks the first time since Kamen Rider OOO that the collectible is used to change something other than itself into the Rider Machine.
      • Unlike OOO, with only the Cell Medals used to initiate the transformation, a more direct reference to the main Rider's power source being responsible for a Rider Machine's activation can be taken from Kamen Rider Ryuki's Final Vent with Dragranzer.
      • Bike Gamer is debatable as while prior instances are drawn directly from the arsenal, the original source of the Rider Machine is a Rider.
  • It is also the first Rider cellphone device to transform into a Rider Machine.
  • The use of a feline-themed trinket to activate a mode change (albeit into the actual Rider Machine) is similar to the use of the Tora Candroid on the Ridevendor.
  • The idea of a email messaging app having the "you've got mail!" audio announcement is a bit dated, as most email systems used that in the 1990s during the dial-up era of the internet such as AOL Mail and modern ones use audible pings or chimes. But a smartphone's notifications can be customized, so it is likely Sento chose that custom notification sound out of personal preference. 



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