|This article is about a/an episode in Kamen Rider Drive.|
Why Did the Siege Happen? (ろう城事件はなぜ起きたのか Rōjyō Jiken wa naze Okita no ka) is the thirty-fifth episode of Kamen Rider Drive.
Mitsuhide Nira, who has been revealed to be the murderer of Eisuke Tomari, takes steps with Brain to hide away the evidence from 12 years ago. Moreover, they hold a press conference, falsely accusing the Special Investigation Unit of colluding with the Roidmudes, landing them in jail and Shinnosuke as the public's most wanted criminal. Shinnosuke must find a way to free the Unit and expose Nira of his crimes.
Police officers storm the Kuruma Driving License Center after a "hostage crisis" happened, where Mitsuhide Nira was "held" by Shinnosuke. In the Special Investigation Unit's office, Shinnosuke finally confronts Nira but of course, as the latter stated, there's no way he would escape. Shinnosuke takes over the narration of the episode, bringing the viewers back from how the siege incident happened.
1:10 PM, 20 hours till the siege
After Nira was confirmed as the killer of Eisuke Tomari only to the Unit, Jun was incapable of tracking Nira, yet furthered by the fact that he is the leader of the First Division, there's no doubt of what schemes he may concoct. Nira now comes into the possession of the gun that he once used to shot Eisuke from 12 years. Shinnosuke and Chase awaited at a hospital where Yukari Karasawa (the girl/eyewitness that Eisuke protected) was sent to, believing she would be Nira's recent target. Chase was given Mad Doctor by Kiriko, anticipating Brain's attack on her would involve poisoning.
While Yukari warmly greeted the two, it was then where she was trapped in a Heavy Acceleration wave and thus, Nira/Thief Roidmude came to attack her as predicted. He somehow synchronized to a new Roidmude but nonetheless, Shinnosuke and Chase transformed as they attacked him, saving Yukari from the wave. Thief demonstrate his ability to unleash poisonous gas, revealing his synchronization as Brain. Yukari was captured by one of Thief's tentacles but Mach arrived in time to rescue her and joined the brawl. In the end, Thief was forced to retreat. Chase volunteered himself to bring Yukari back to home while Shinnosuke track Nira and Brain.
Brain is gleefully expecting Medic to arrive and reveals his Over Evolved State while threatening to address him with greater respect. Refusing to bow to his superiority, Medic challenged him but is overpowered by his newfound monstrous ability. Heart appears and praises Brain for his upgrade as Brain is likewise overjoyed for gaining Heart's respect and finally overthrowing Medic as Heart's loyal comrade. He soon set his eye on Shinnosuke.
6:47 PM, 14 hours 23 minutes till the siege
That evening, Shinnosuke wondered where Nira had hid himself while on the rooftop gazing the sunset scenery. Captain Jun appeared, where he revealed that what he did earlier was similar to him and his father in their earlier days as officers. Chase decided to let Yukari walked on her own but sees a strange rash on her arm that came from Thief after she was captured, he insisted Shift Speed Prototype to watch over her. Jun actually had kept a huge regret after witnessing Eisuke's fortune the day before he died: "Super Unlucky". Jun never told him the prediction and thus, he lost his life. After meeting Krim and found that his death was covered up by a large conspiracy, he swore to uncover it as much as possible.
Despite the case became harder to solve over time, now with his son Shinnosuke succeeded him as an officer and too the mantle of Kamen Rider, the true killer was nearly brought to justice. Shinnosuke swears to put an end to Nira's schemes and Jun affirmed that his friends would support him no matter what. Kiriko appeared and alarmed them of a conference meeting held by Nira and Sou Noumi (Brain) on television.
7:10 PM, 14 hours till the siege
During the conference, Nira and Brain made a false investigation where 12 years ago during the robbery, Makage was the "true" culprit by the name of 001/Freeze Roidmude, leader of the Mechanical Life Forms that officer Shinnosuke Tomari/Kamen Rider Drive was fighting. However after reviewing his files, it was "revealed" that a "power struggle" happened between the leadership of the race. Kamen Rider Drive was actually fighting over their leadership and was backed up by the Special Investigation Unit. Brain and Nira had used the Unit members' relation with Roidmudes (Rinna with Voice Roidmude, Genpachiro with Judge Roidmude, Kyu with Roidmude 072 and lastly, Kiriko's relation with Chase, whose background as an evil Roidmude bounty hunter, Mashin Chaser). The hoax news was viewed by everyone, including Chase and Go.
Nira, now the leader of the National Bureau of Defense, issued the dissolution of Special Investigation Unit and capture of Kamen Rider Drive and his associates. Simultaneously, police officers ordered by Brain tried to capture the Unit but Jun and the others made a quick move to ensure Shinnosuke's escape, willingly sacrificing themselves. With Shinnosuke escaped, Brain and Nira launched their next move.
7:23 AM, 1 hour 47 minutes till the siege
The next morning, Shinnosuke tried his best to avoid incoming police officers. Taking refuge under a bridge, Mr. Belt (under a comedic robot combination by the Shift Cars) comforted Shinnosuke, confirming that his bonds with his friends had help him entered his greatest succession. Nira/Thief revealed himself to Shinnosuke, as the two fought with Kamen Rider Chaser joined the battle and separated Nira from Brain, seemingly killed the latter. But Brain survived and entered his Over Evolved State and overpowered the Riders. Chaser dealt with Brain while Shinnosuke chased Nira to the Special Investigation Unit's office. Shinnosuke finally cornered Nira in the Unit's office, but Nira calmly armed himself with the similar gun that he used to kill Eisuke.
8:55 AM, 15 minutes till the siege
Brain had finally defeated Chaser and revealed that even if he wanted Chase dead, there would be a task that only he would fulfill in the future before he took his leave. Nira finally revealed his latest trick: he faked a hostage crisis at the Kuruma Driving License Center. Yukari, whom was watching the news in public succumbed into the poison delivered by Thief a day ago. The Shift Speed Prototype Car witnessed this and went to report to Chase.
Go now realized what terrible danger Shinnosuke is in and requests his father's help but Heart comes in and tries to reclaim Banno.
9:10 AM, Siege in progress
Police officers and SAT brigades surround the driving school, with Shinnosuke and Mr. Belt realized too late. Nira pointed his gun at Shinnosuke, claiming that he will take his life in one hour.
- Shinnosuke Tomari (泊 進ノ介 Tomari Shinnosuke): Ryoma Takeuchi (竹内 涼真 Takeuchi Ryōma)
- Kiriko Shijima (詩島 霧子 Shijima Kiriko): Rio Uchida (内田 理央 Uchida Rio)
- Chase (チェイス Cheisu): Taiko Katono (上遠野 太洸 Kotono Taiko)
- Go Shijima (詩島 剛 Shijima Gō): Yuu Inaba (稲葉 友 Inaba Yuu)
- Jun Honganji (本願寺 純 Honganji Jun): Tsurutaro Kataoka (片岡 鶴太郎 Kataoka Tsurutarō)
- Rinna Sawagami (沢神 りんな Sawagami Rinna): Rei Yoshii (吉井 怜 Yoshii Rei)
- Kyu Saijo (西城 究 Saijō Kyū): Kenta Hamano (浜野 謙太 Hamano Kenta)
- Genpachiro Otta (追田 現八郎 Otta Genpachirō): Taira Imata (井俣 太良 Imata Taira)
- Mitsuhide Nira (仁良 光秀 Nira Mitsuhide): Kisuke Iida (飯田 基祐 Iida Kisuke)
- Narration (ナレーション Narēshon), Drive Driver's voice (ドライブドライバーの声 Doraibu Doraibā no koe): Chris Peppler (クリス・ペプラー Kurisu Pepurā)
- Heart (ハート Hāto, Voice): Tomoya Warabino (蕨野 友也 Warabino Tomoya)
- Brain (ブレン Buren): Shota Matsushima (松島 庄汰 Matsushima Shōta)
- Medic (メディック Medikku): Fumika Baba (馬場ふみか Baba Fumika)
- Tenjuro Banno (蛮野 天十郎 Banno Tenjūrō, Voice): Masakazu Morita (森田 成一 Morita Masakazu)
- Yukari Karasawa (唐沢 ゆかり Karasawa Yukari): Coco Koizumi (小泉 ここ Koizumi Koko)
- Reporter: Izumi Okawara (大河原 生純 Ōkawara Izumi)
- TV Announcer: Hidetoshi Wakabayashi (若林 秀俊 Wakabayashi Hidetoshi)
- Police: Kanji Obana (尾花 かんじ Obana Kanji)
- SAT Captain: Naoki Inotsume (猪爪 尚紀 Inotsume Naoki)
Shift Cars & Signal Bikes
- Car Used:
- Type Change: Shift Tridoron (once attempted), Shift Speed
- Tire Exchange: N/A
- Type Used:
- Type Tridoron (once attempted), Type Speed
- Tire Blending used in Type Tridoron:
- Attack 1.2.3
- Bike Used:
- Form Change: Signal Mach
- Signal Exchange: N/A
- Form Used:
- Form Change: Signal Chaser
- Form Used:
- As part of Super Hero Time, this episode aired alongside Shuriken Sentai Ninninger episode 18, Shinobi 18: The Youkai That Yakumo Loved.
- Viewership: 5.3%
- Closing Screen Shift Car/Signal Bike
- Roidmude Count
- Answer to the episode's question: Due to Nira and Brain wanting to frame the Special Investigation Unit.
- This marks the first time since his 'brainwashing' that Go has said "Let's Transform" when transforming into Deadheat Mach.
- While Go watches the newscast, he can been seen using an iPhone 6.
Kamen Rider Drive Volume 9 features episode 33-36: Who Claimed the Life of Shinnosuke Tomari?, Who Claimed the Life of Eisuke Tomari?, Why Did the Siege Happen? and Where Will the Bullet Guide Justice? 
Collection 3 comes with 12 episodes.