|This article is about a/an character in Kamen Rider Build.|
Following his director Gentoku Himuro, Matsui was part of a cabal of scientists of the Touto Institute of Advanced Matter Physics who sought to continue Takumi Katsuragi's officially suspended research into Nebula Gas in 2015. Alongside Yoshikazu Takahashi, Matsui introduced himself to Katsuragi as his assistants. When Gentoku named the group Faust, Matsui was among the personnel who cheered him on.
- "Gear Engine! Funky! (Rock music, engine revving) Engine Running Gear!"
- ―Transformation announcement[src]
- Height: 203.0 cm.
- Weight: 103.5 kg.
- Punching Power: 30.2 t.
- Kicking Power: 37.2 t.
- Maximum Jump Height: 48.6 m.
- Maximum Running Speed: 100 m. per 1.7 sec.
One half of the Hell Bro's, Engine Bro's (エンジンブロス Enjin Burosu) is the white Kaiser, transformed into by inserting the Gear Engine into the Nebulasteam Gun. This updated Kaiser System was created by Nariaki Utsumi, based on that originally developed by Kaisei Mogami.
Engine Bro's is composed of the following parts:
- Engine Bro's Head (エンジンブロスヘッド Enjin Burosu Heddo) - The helmet.
- Engine Dark Visor (エンジンダークバイザー Enjin Dāku Baizā) - The engine-like visor covering the entire left side of the helmet. It is a shock-resistant frame that has been stretched to demonstrate high defensive capabilities against physical attacks.
- Grudge Signal (グラッジシグナル Gurajji Shigunaru) - The white gear on the forehead. When the user's level of anger surges, the chest-mounted Nebula Generator is operated at a higher rate, resulting in increased combat ability.
- Dusk Seeker Eye (ダスクシーカーアイ Dasuku Shīkā Ai) - The red eye. It is a highly sensitive sensor that can detect a moving body's reaction and heat sources. It is also capable of night vision, chemical detection and can examine enemy traces.
- EB Side Blade (EBサイドブレード EB Saido Burēdo) - The antenna. It can collect information in realtime to grasp the capabilities of enemies. It also manages the body's condition and automatically repairs any broken or damaged areas.
- EB Face Guard (EBフェイスガード EB Feisu Gādo) - A defensive gear located around the mouth and chin area. It can release a special wave to weaken an enemy's energy attack, minimising damage.
- Air Face Duct (エアフェイスダクト Ea Feisu Dakuto) - Exhaust devices/air filters located around the chin area. When air is breathed in, harmful substances are removed. It can discharge any taken toxins back into the environment.
- Cog Chest Armor (コグチェストアーマー Kogu Chesuto Āmā) - The robust chest armor. It has a built-in Nebula Generator (ネビュラジェネレーター Nebyura Jenerētā) which can produce special steam that enhances Remocon Bro's' fighting ability by temporarily speeding up movements to increase attack power.
- Gear Steam Shoulder (ギアスチームショルダー Gia Suchīmu Shorudā) - The right shoulder armor. It optimises arm movement to increase attack efficiency. It can scatter colored gas through armor gaps.
- EB Unlimited Suit (EBアンリミテッドスーツ EB Anrimiteddo Sūtsu) - The shockproof bodysuit. Along with protecting the wearer’s body, there is a limiter installed that can be released to bring out full physical ability.
- Punishment Arms (パニッシュメントアーム Panisshumento Āmu) - The arms. They combine power and speed, and is capable of rapid punches and elbow blows.
- Gear Torque Gauntlet (ギアトルクガントレット Gia Toruku Gantoretto) - A special device mounted on the right forearm. It can generate special energy cutters in the form of gears to launch at enemies.
- Dominate Gloves (ドミネイトグローブ Domineito Gurōbu) - The reinforced hands. It's shape makes it suitable for melee attacks, and is capable of thrusting attacks thanks to its sharp claw-like fingertips.
- Puishment Legs (パニッシュメントレッグ Panisshumento Reggu) - The legs. They combine power and speed, and is capable of continuus kicks and high-knee kicks.
- Metal Knee Bat (メタルニーバット Metaru Nī Batto) - The knee armor. Optimises leg movement to improve their speed.
- Aidron Shoes (アイドロンシューズ Aidoron Shūzu) - The feet. They are good at quick and quiet movements, allowing Engine Bro's to quickly sneak up to enemies. A special steam can be dispersed from the tips to create afterimages, disorienting opponents.