|This article is about a/an episode in Kamen Rider Hibiki.|
Weakening Thunder (鈍る雷 Niburu Ikazuchi) is the fifteenth episode of Kamen Rider Hibiki. It features the first appearance of three Oni: the apprentice Tomizo Todayama as "Todoroki", his master Zaomaru Zaitsuhara as "Zanki" and another Oni Sabaki.
Asumu returns home after spending a week hospitalized and begins his recuperation. Elsewhere, Zanki reveals that he will soon be retiring and expects his apprentice Todoyama to take his place, a revelation that Todoyama is less than pleased with. Even more, they are called to aid Sabaki at Tsukama Village, where a Yamaarashi is running rampant.
Asumu is back home and checking on his scar when Hitomi call on his phone. The two chat about how he is doing and Hitomi invites him out for an afternoon walk which he accepts. He tucks his hand in his pants to check his scar when his mother walks in, and hastily leaves, confusing him.
Tomizo Todayama and Zanki arrives at the location for their current search and hastily sets out from their car. Meanwhile, a group of fishermen are walking down a road when one of them needs to go on the toilet and heads into the bushes. As he keeps walking he stumbles upon a Bakegani Douji and Hime. Disc Animals arrive and the Oni shortly afterwards. Zanki pardons the boy as he throws him away to his disciple. The Douji and Hime says they will have to punish him for getting in their way as Zanki unsheets his Ongekigen. Tomizo joins him and they both transform as the Douji and Hime rushes towards them. The transformation sends a jolt through the Makamou pair and sends them flying. They engage in hand to hand combat with the monsters and Tomizo wrecks the claw of the Hime but Zanki was unable due to his leg injury. He picked up the Ongekigen and the Douji retreated. His student threw the Douji at him to cut, but Zanki missed his first strike as his leg gave away, but he quickly struck again and killed it. They both started to give chase to the fleeing Douji.
Hibiki, Ibuki and Akira were on a training run when Hibiki stopped at a motorcycle shop. Ibuki greatly admired the bikes with Hibiki, and the former thought a bike would fit Hibiki perfectly. He said he would do his best to learn how to drive then. Akira reminded him of before when he did not know how to stop a bike which made him silent.
Tomizo had lost the track of the Douji and apologised to his master. The Douji was nearby however as it started to push boulders down at them. Tomizo broke one boulder with a punch and as it went to push down another one, Zanki threw the Ongekigen through the boulder and the Douji as well, killing it. The Bakegani then suddenly attacked and Zanki retaliated by first cutting of its claws and then stabbing it with the Ongekigen. He attached the Ongekishin to the Ongekigen, which extended its wings, but as he was about to strike a chord, his leg gave away. The Bakegani shook him of and went after him in the water. Zanki stabbed it again and tipped it over enabling him to strike a chord which made it explode. The exhausted Zanki staggered onto the beach and laid down.
Ibuki and Akira was in the meanwhile training their forms when Hibiki arrived with some snacks. Hibiki commended Akira's commitment and progress in training and wondered if it was due to her willforce. She said it was due to Ibuki's guidance, and as she had heard that Hibiki's training was fast she asked if it was true. He was ambiguous about it and asked if her next step was to become an Oni. She confirmed it as she was currently on the sixth level. Akira wanted to transform soon, but Ibuki had said that it was not good to rush. Hibiki said it was true, and ibuki was young as well so there was no need to rush.
Kasumi and Hinaka were decorating the Tachibana Sweet Place store for spring and making a note that they wanted a part timer. Tomizo called and Hinaka answered with glee and he told her of the Bakegani. She complimented both him and Zanki and wondered if she would be his combo soon. Tomizo handed the phone as she kept ranting about their combo until Zanki asked if Ichirou Tachibana was there. The let-down Hinaka said he was not there, so Zanki told her directly that he was quitting being an Oni and that Tomizo would take over for him. Tomizo was in shock.
Asumu was in his kitchen and read a not from his mother that said she was out to buy some things. Hibiki, Ibuki and Akira were perusing in a supermarket where Hibiki tried to learn them bargain tips. As he went to grab some produce he stumbled upon Asumu's mother. A Black Puppet was at the same time standing in a shadowy forest and injected a Yamaarashi Douji and Hime to life.
Tomizo was still very unhappy by Zanki's choice to quit and asked why he had not told him before. He thought Zanki might have told Hibiki about it, but he said that he had just decided it as his leg was not working as it should. He thanked his student for being there today, and that from now on he entrusted everything to Tomizo. Tomizo tried to needlessly protest and fell into a bush in the process.
Asumu was reading in bed when his mother came home in a fuzz. Asumu asked what was wrong and she told him to help clean the place up as Hibiki could not be allowed to see it. Asumu rushed to clean his room as well.
Kasumi and Hinaka were sitting in the store when Ichirou came back and told him that Zanki would call soon. The phone rang, but it was Ishiwari, Sabaki's supporter who said the Oni was in a bad condition and might not be able to defeat their next opponent, so he asked Ichirou if he could do something. Kasumi suggested they send Hibiki, but Ichirou said they were dealing with a Yamaarashi and would have to use a guitar against it. He decided to go with Zanki who was the closest and would talk with him about his retirement first.
Tomizo and Zanki were driving in their car when the former apologised for his earlier behaviour. As he was about to explain himself Ichirou Tachibana called. He confirmed Zanki's retirement, but asked him to deal with the Yamaarashi that was close by. Zanki had not seen Sabaki in a year and said that he would do it.
Sabaki had dropped his Ongekigen and was fighting the Yamaarashi Douji and Hime. He kept fighting but hist stamina was severely depleted when suddenly the Yamaarashi itself appeared.
Zanki and Tomizo speedily arrived at the village where they came upon the Yamaarashi in the outskirts. Sabaki was unconscious and wrapped in the Makamou's tail. As they approached it, the Douji and Hime appeared. The two transformed, but Zanki's leg was still bad.
- Hibiki (響鬼（ヒビキ） Hibiki): Shigeki Hosokawa (細川 茂樹 Hosokawa Shigeki)
- Asumu Adachi (安達 明日夢 Adachi Asumu): Rakuto Tochihara (栩原 楽人 Tochihara Rakuto)
- Ibuki (威吹鬼（イブキ） Ibuki): Joji Shibue (渋江 譲二 Shibue Jōji)
- Todoroki (轟鬼（トドロキ） Todoroki): Shingo Kawaguchi (川口 真五 Kawaguchi Shingo)
- Zanki (斬鬼（ザンキ） Zanki/Kamen Raidā Zanki): Kenji Matsuda (松田 賢二 Matsuda Kenji)
- Kasumi Tachibana (立花 香須実 Tachibana Kasumi): Mayu Gamou (蒲生 麻由 Gamō Mayu)
- Hinaka Tachibana (立花 日菜佳 Tachibana Hinaka): Miyuki Kanbe (神戸 みゆき Kanbe Miyuki)
- Hitomi Mochida (持田 ひとみ Mochida Hitomi): Erika Mori (森 絵梨佳 Mori Erika)
- Ikuko Adachi (安達 郁子 Adachi Ikuko): Kaoru Mizuki (水木 薫 Mizuki Kaoru)
- Ichirou Tachibana (立花 勢地郎 Tachibana Ichirō): Atomu Shimojo (下條 アトム Shimojō Atomu)
- Akira Amami (天美 あきら Amami Akira): Nana Akiyama (秋山 奈々 Akiyama Nana)
- Douji (童子 Dōji): Mitsu Murata (村田 充 Murata Mitsu)
- Parent Douji : Sei Ashina
- Hime (姫 Hime): Sei Ashina (芦名 星 Ashina Sei)
- Parent Hime : Mitsu Murata
- Next Preview Narrator (次回予告ナレーター Jikai Yokoku Narētā): Kazuya Nakai (中井 和哉 Nakai Kazuya)
- Junction Narrator (ジャンクションナレーター Jankushon Narētā): Koji Nakata (中田 浩二 Nakata Kōji)
- Student: Shion Tsuchiya (土屋 シオン Tsuchiya Shion)
- Keizo Yabe (矢部 敬三 Yabe Keizō)
- Keiko Hashimoto (橋本 恵子 Hashimoto Keiko)
- Jun Watanabe (渡辺 淳 Watanabe Jun)
- Yoshifumi Oshikawa (押川 善文 Oshikawa Yoshifumi)
- Makoto Ito (伊藤 慎 Itō Makoto)
- As part of Super Hero Time, this episode aired alongside Mahou Sentai Magiranger episode 13, Stage 13: If I Were Mother.
- Viewership: 7.4%
- This is the first time seeing Todoroki's Kitōjutsu: Raigekiken technique.
- Shion Tsuchiya would later portray JK in Kamen Rider Fourze.