This article is about a/an character in Kamen Rider Build.

Kasumi Ogura (小倉香澄 Ogura Kasumi) is Ryuga Banjo's late-fiancé and one of the victims of Faust's experiments who got turned into the Burn Smash (バーンスマッシュ Bān Sumasshu). Her Smash essence was used as the basis for the Dragon Full Bottle.

Character History

Kasumi suffered from an unspecified illness. It is implied that her fiancé Ryuga accepted a bribe to help pay for her medical treatments, which got him banned from professional fighting. Sometime later, Kasumi was approached by Masahiro Nabeshima, who told her to direct Ryuga to Takumi Katsuragi, promising to help Ryuga make a comeback in return. Kasumi agreed, and brought up Katsuragi on her next date with Ryuga. However, when Katsuragi was found dead, Ryuga was framed for the murder and sentenced to ten years in prison.


One year later, soon after Ryuga's escape from prison, Kasumi was kidnapped by Faust. Kasumi received a call from Ryuga seconds before forcibly undergoing a transformation into the Burn Smash. Her consciousness suppressed, the Burn Smash attacked Ryuga when he came to find Kasumi. Sento soon arrived, but was interrupted by Night Rogue, who easily overwhelmed him as Build. Night Rogue gave Ryuga and Build a grim warning: due to her frail body, Kasumi was deemed a "Hazard Level 1", meaning that it would be impossible to return her to her human form without killing her in the process.

While Ryuga tried to stop Build from finishing the Smash, Kasumi's consciousness began to fight off the Smash persona, causing it to misfire when it tried to attack Ryuga. Realizing that it was too late to save her, Ryuga begged Build to end Kasumi's suffering. Using the GorillaMond form, Build was able to temporarily separate Kasumi from the Burn Smash, allowing her and Ryuga to say their goodbyes. Soon, Kasumi's consciousness faded, and Build extracted the Burn Smash's essence. The harvested essence was purified into the Dragon Full Bottle, which Sento gave to Ryuga as a memento of his beloved.

New World

NW Ryuga & Katsumi

A new version of Kasumi exists in the new world. As she and her boyfriend, the new world version of Ryuga are walking, Sento Kiryu approaches them, saying that he was glad Ryuga was alive. Confused, Kasumi thinks Sento is one of Ryuga's MMA fans, and Ryuga offers to shake hands, which Sento agreed to. As Sento walks off, Ryuga and Kasumi run off to get ice cream.

Upon meeting up with Sento, the original Ryuga also mentions that he spotted the alternate versions of himself and his girlfriend.

When Killbus reactivated Pandora's Box, everyone who were directly exposed to Nebula Gas in the original World of Build regained their memories from that world, theoretically also including Kasumi.Kamen Rider Build NEW WORLD: Kamen Rider Cross-Z

Powers and Abilities

  • Pyrokinesis: As its name said, it has the powers to freely generate fire.
    • Fire Ball Projection: It can release fire balls from its cannons to attack its enemies.
    • Flamethrower: It can release a fire wave from its cannons to attack its enemies.
  • Retained Consciousness: Unlike other Smash, Kasumi managed to retain some of her consciousness while in her Smash form: she misfired when attempting to shoot Ryuga.


  • Hazard Level 1: Unlike other Faust victims, Kasumi's body is too weak to survive the Smash transformation. As a result, extracting her Smash essence cost Kasumi her life.

Burn Smash

Burn Smash
KRBu-Burn Smash
  • Height: 207.0
  • Weight: 121.0

Smash Bottle

Burn Smash Bottle

Smash Bottle
(Burn Smash)

This Smash Bottle contains the essence of the Burn Smash.

Behind the scenes


Kasumi Ogura was portrayed by Risako Ito (伊藤 梨沙子 Itō Risako),As Burn Smash, her suit actor is Hajime Kanzaki (神前元 Kanzaki Hajime).

Concept Art

Burn Smashart

Burn Smash concept art


  • Kasumi is very similar to Saki Momose from the previous season as:
    • Both girls were loved ones to secondary Riders and died in front of them prior to their becoming Riders.
      • Their deaths were the main reason why their loved ones became Kamen Riders and decided to fight the responsibles of their deaths.
      • Both wanted them to get the best of themselves even if they (Saki and Kasumi) had to lie to them (Saki lied to Hiiro about her condition in order to not distract him from his studies and Kasumi lied to Ryuga about how she obtained the information about the job offer that lead him to be framed for murder in order to get him back his wrestler license).
    • Both were victims of the villain groups actions that resulted in the creation of monsters themed after a dragon (Burn Smash for Kasumi, Graphite Bugster for Saki).
      • The leaders of those groups personally created those monsters from them (Kuroto infected Saki with an overdose of the Bugster Virus to provoke stress on her to create Graphite while Gentoku as Night Rogue personally turned Kasumi into the Burn Smash).
    • Both girls were unable to be saved from those monsters by a Kamen Rider which resulted in their deaths.
    • Their deaths connect with dragon-themed collectible items (Drago Knight Hunter Z Gashat and Dragon Full Bottle).
    • Unlike Saki, Kasumi died during the events of the series.
      • On the final episode, Kasumi was seen in a new world without Evolto, as opposed to how Saki's revival occurred in a special outside of the main show.


Sento Kiryu (Takumi Katsuragi) - Ryuga Banjo - Kazumi Sawatari - Gentoku Himuro - Evolto - Nariaki Utsumi - Shinobu Katsuragi
Movie-exclusive: Kengo Ino - Killbus - Keiji Uraga
Transformation Gear
Fullbottles - Build Driver - Transteam Gun - (Great) Cross-Z Dragon - Sclashjellies - Sclash Driver - Hazard Trigger - Nebulasteam Gun - Cross-Z Magma Knuckle - Evol-Driver - Evol-Trigger - Grease Blizzard Knuckle - Killbuspider - Grease Perfect Kingdom
Drill Crusher - Hawk Gatlinger - 4Koma Ninpoutou - Kaizoku Hassyar - Fullbottle Buster - Steam Blade - Beat Closer - Twin Breaker - Muscle Glove - Solstall Wings - Giant Scratcher - Space Ride Arm - Spine Knuckle - Long Range Cleaner - Trash Converter - Gold Lio Gauntlet - Multi Deluge Gun
Pandora Box - Halfbodies - Fullbottle Holder - Build Phone
Vortex Finish - Hazard Level - Project Build - Sky Wall - Nebula Gas
nascita: Misora Isurugi - Soichi Isurugi - Sawa Takigawa - Kazumi Sawatari - Gentoku Himuro
Kamen Riders: Eiji Hino - Gentaro Kisaragi - Kouta Kazuraba - Takeru Tenkuji - Emu Hojo - Hiiro Kagami - Taiga Hanaya - Kiriya Kujo - Kuroto Dan - Parado - Sougo Tokiwa - Geiz Myokoin - Tsukuyomi
Prime Ministers: Taizan Himuro (Touto) - Yoshiko Tajimi (Hokuto) - Masakuni Mido (Seito)
Namba Heavy Industries Ltd.: Juzaburo Namba - Nariaki Utsumi - Haruhiko Wanibuchi - Guardian
Hell Bro's: Fu Washio - Rai Washio - Yoshikazu Takahashi - Norio Matsui
Aliens: Vernage
Gentoku Himuro - Evolto - Nariaki Utsumi - Takumi Katsuragi - Shingo Kuwata - Eita Kawai - Yoshikazu Takahashi - Norio Matsui
Touto: Needle Smash - Strong Smash - Burn Smash - Flying Smash - Mirage Smash - Square Smash - Press Smash - Ice Smash - Stretch Smash
Hokuto: Castle Hard Smash - Stag Hard Smash - Owl Hard Smash
Kaiser: Kaisei Mogami (World of Ex-Aid)
Kengo Ino - Ryoka Saiga - Mitsuomi Gobara - Evolto - Killbus
Keiji Uraga - Simon Marcus (Phantom Crusher)
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