Seikin

Japanese YouTube celebrity and singer-songwriter (born 1987)

Seikin

Seikin in 2020

Personal information
Born|

Seiya Kaihatsu

(1987-01-30) January 30, 1987 (age 38)

Myōkō, Niigata, Japan

Occupations|

* Singer songwriter
* YouTuber

Spouse|

Undisclosed

(m. 2014)​

[1]
Relatives| Hikakin
YouTube information
Channels|

* SeikinTV
* SeikinGames

Years active| 2012–present
Subscribers|

* SeikinTV : 4.77 million
* SeikinGames : 1.45 million

Total views|

* SeikinTV : 4.7 billion
* SeikinGames : 737 million

Network| UUUM

Creator Awards

| 100,000 subscribers| 2013
| 1,000,000 subscribers| 2015

* * *

Last updated: February 16, 2025

Seiya Kaihatsu (Japanese: 開發 聖也, Hepburn: Kaihatsu Seiya, born July 30, 1987) professionally known as Seikin (Japanese: セイキン), is a Japanese YouTuber and singer-songwriter. His younger brother is YouTuber Hikakin, who is also a member of the Japanese music group Hikakin & Seikin.[2]

## Early life

[edit]

On July 30, 1987,[3] he was the eldest son to his parents in Myōkōkōgen, Nakakubiki District, Niigata Prefecture (present Myōkō City, Niigata Prefecture).[4] As a child he longed to be a baker because of his favorite food, bread. The first video he uploaded to YouTube as "SeikinTV" was "Morning is Bread.[‡ 1] In 2000, he entered a local junior high school, where he was a member of an a cappella group from the first year of junior high school and also joined the brass band, playing the trombone.[‡ 2] At high school he switched from the brass band and joined the ski club,[‡ 3] where he placed fourth in the inter-high school ski jump competition.[5] His younger brother Hikakin recalls Seikin in high school, "Unlike me, he studied for an hour every day, even before a test".[‡ 4]

After graduating from high school, I moved to Tokyo and enrolled in the Faculty of Letters at Senshu University,[6] but I realized that this was not the path I wanted to follow and dropped out.[5] After that, I worked as a part-time worker for about four years, but I realized that this lifestyle was not good, so I got a job at a company.[5]

## Career

[edit]

In 2012, influenced by his younger brother Hikakin, who was expanding his activities as a YouTuber on the video site, he opened the "SeikinTV" channel on YouTube.[7]

On March 2 of the same year Seikin uploaded "Morning is Bread," a song written and performed a cappella by Seikin himself, marking his start as a YouTuber.[8] He initially called himself an "a cappella musician," and the name "Seikin" came from a suggestion he made to his younger brother Hikakin: "I'm Hikakin, so why not Seikin?".[‡ 5]

In 2014, his income from YouTube exceeded his salary as an office worker, and he began to work on YouTube in earnest.[7] He then quit his job to focus on YouTube and began working as a YouTuber.[5] On February 10 of the same year, he joined the Japanese multi-channel network Uuum.[9]

On August 14, 2015, he released "YouTube Theme Song," which he co-wrote with his brother Hikakin. This marked the start of his musical career as Hikakin & Seikin.[10] "YouTube Theme Song" reached number 78 on the Billboard Japan Hot 100.[11] As of 2024, the music video has been viewed over 140 million times, making it the most viewed video on his brother Hikakin's channel, "HikakinTV".[12]

On November 7th of the same year, he released his own song "Just Do It Now",[13] and on July 30th of the following year, 2016, he released another solo EDM-style song, "Keep Your Head Up".[14] The former "Just Do It Now" reached 5th place in the iTunes Overall Album Ranking,[13] while the latter "Keep Your Head Up" only reached 4th place in the iTunes Overall Album Ranking.[14] In the same year, the number of subscribers to the "SeikinTV" channel reached 1 million, and YouTube awarded him the "Gold Creator Award",[‡ 6] and the following year in 2017, "SeikinGames" was awarded the "Gold Creator Award".

On March 18, 2022, Seikin's TikTok account was hijacked by an unknown individual, and all videos he had posted were deleted.[15] Viewers who noticed the situation contacted his agency Uuum with numerous inquiries, and TikTok management, his agency, and the police immediately worked together to quickly respond. Thanks to their efforts, they were able to get their account back two days later. The next day, all of his videos were restored.[16]

## Personal life

[edit]

On December 25, 2014 he reported in his video that he had entered into a marriage and married a civilian woman of the same age with whom he had been dating for two and a half years.[‡ 7][‡ 8] Two years later, in 2016, they had a wedding ceremony that also included a honeymoon in the state of Hawaii in the United States.[‡ 9] He commented that the secret to a happy marriage is to "think of the other person's feelings before your own." He commented.[‡ 10]

In April 2018, he announced the birth of his first child on his official YouTube channel.[‡ 11] When he went into labor, he contacted his brother via Line, and Hikakin rushed to the hospital. He also posted footage of the birth on YouTube, which became a hot topic.[8]

On May 29, 2020, Seikin purchased a Ferrari F8 Tributo for 33.28 million yen.[17] On August 28, 2023, Seikin reported that he had purchased a Lamborghini Urus for 40 million yen (about $270,000).[18][19][20]

## Discography

[edit]

Main article: Hikakin & Seikin § Discography

### Singles

[edit]

Title  | Year  | Peak chart positions  | Album

|
|
|

JPN

Hot
[21]

"Just Do It Now"  | 2015  | —  | Non-album single
"Keep Your Head Up"  | 2016  | —

## References

[edit]

### Secondary sources

[edit]

1. ^ "SEIKIN、3歳息子&愛車・レクサスと3ショット「チビキンくん大きくなってる」「かっけー!」「親子仲良し素敵」". ORICON NEWS. 25 June 2024. Retrieved 2025-02-15.
2. ^ 編集部. "HIKAKINとSEIKIN「兄弟だったの？」Mステでのパフォに興奮の声". MusicVoice (in Japanese). Retrieved 2023-06-13.
3. ^ Shimbun, The Nishinippon. "セイキン「元気そうでよかった！」誕生日を迎え海での自撮りにヒカキンもコメント＆SNSは安堵の声で溢れる：「おっ！」でつながる地元密着のスポーツ応援メディア 西スポWEB OTTO!". 「おっ！」でつながる地元密着のスポーツ応援メディア 西スポWEB OTTO! (in Japanese). Retrieved 2025-02-15.
4. ^ joetsutj (2010-09-20). "ハモネプに出たHIKAKINさんは妙高市出身". 上越タウンジャーナル (in Japanese). Retrieved 2023-06-13.
5. ^ a b c d "SEIKIN：第1回「オリンピック選手を目指した過去、YouTuberになったのは？」". ライブドアニュース (in Japanese). Retrieved 2025-02-16.
6. ^ "ニュース専修ウェブ版2006年4月号（第427号）＿14–15面" (PDF). Retrieved 2023-06-05.
7. ^ a b "SEIKIN「会社員の収入を上回ったことをきっかけに…」YouTuberになりたての2014年当時を振り返る". MSN News. Retrieved 2025-02-15.
8. ^ a b Kashima, Yui (2018-12-28). "ヒカキン兄セイキン。同業者に嫉妬はしない。家族は顔出ししない。深い理由". BuzzFeed News (in Japanese). Retrieved 2025-02-15.
9. ^ UUUM株式会社（ウーム株式会社） (2014-02-09). "SEIKIN、レオンチャンネルがUUUMに加入！". UUUM株式会社（ウーム株式会社） (in Japanese). Retrieved 2025-02-16.
10. ^ "YouTuber HIKAKIN＆兄SEIKINがYouTubeテーマソングをリリース". BARKS (in Japanese). 2015-08-14. Retrieved 2025-02-15.
11. ^ "Billboard Japan Hot 100 | Charts". Billboard JAPAN (in Japanese). Retrieved 2025-02-15.
12. ^ "SEIKIN「HIKAKINから急に無茶ぶりが来て…」"兄弟ユニット"『HIKAKIN ＆ SEIKIN』デビュー裏話（TOKYO FM＋）". Yahoo!ニュース (in Japanese). Retrieved 2025-02-15.
13. ^ a b "SEIKIN初のオリジナルソロ曲がiTunesエレクトロニックALチャート1位獲得！ | UUUM(ウーム)". UUUM(ウーム) (in Japanese). Retrieved 2025-02-15.
14. ^ a b "SEIKINが2ndシングル「Keep Your Head Up」をリリース！ | UUUM(ウーム)". UUUM(ウーム) (in Japanese). Retrieved 2025-02-15.
15. ^ "セイキンのTikTokが乗っ取り被害 一時全動画が削除「僕にとって動画は宝」". KAI-YOU | POP is Here . (in Japanese). 2022-05-06. Retrieved 2025-02-15.
16. ^ "セイキンのTikTokが乗っ取られ、ヒカキンも怒り 過去にはほかの有名クリエイターも被害に". Real Sound｜リアルサウンド テック (in Japanese). 2022-05-09. Retrieved 2025-02-15.
17. ^ "セイキン、3000万円超えのフェラーリに"飛び石対策"施す 高級車コレクターらしからぬ自然体が人気の秘密？". Real Sound｜リアルサウンド テック (in Japanese). 2021-02-06. Retrieved 2025-02-16.
18. ^ "HIKAKINの兄・SEIKIN、"総額4000万円"のランボルギーニ ウルスを購入「さすが」「憧れる」の声 - モデルプレス". モデルプレス - ライフスタイル・ファッションエンタメニュース (in Japanese). 2022-03-29. Retrieved 2025-02-16.
19. ^ "SEIKIN"総額4000万円"ランボルギーニ ウルス納車 豪華内装にHIKAKIN驚き「いや～、センスいいなぁ！」". ORICON NEWS. 2023-08-29. Retrieved 2025-02-16.
20. ^ "セイキン、4000万円のランボルギーニ ウルスを購入 「日常使いができるスーパーカーが欲しかった」". Real Sound｜リアルサウンド テック (in Japanese). 2023-08-28. Retrieved 2025-02-16.
21. ^ "SEIKIN | Billboard JAPAN". Billboard Japan. Retrieved 2025-02-16.

###  Primary sources

In the text these references are preceded by a double dagger (‡):

1. ^ 朝はパン Morning is Bread, 2 March 2012, retrieved 2023-06-13
2. ^ "SEIKINのツイート". Twitter. Retrieved 2023-06-13.
3. ^ "SEIKINのツイート". Twitter. Retrieved 2023-06-13.
4. ^ ヒカキンとセイキンの高校時代のノートを発見！, 31 January 2015, retrieved 2023-06-13
5. ^ "- YouTube". www.youtube.com. Retrieved 2023-06-13.
6. ^ SeikinTV (2016-07-01). YouTubeから金の再生ボタンが届くドッキリ？. Retrieved 2025-02-15 - via YouTube.
7. ^ 嫁の誕生日なので超巨大10段ケーキ作ります！おめでとう！, 21 April 2015, retrieved 2023-06-13
8. ^ セイキン結婚いたしました。, 25 December 2014, retrieved 2023-06-13
9. ^ ハワイで結婚式を挙げました。【セイキン&ポンちゃん】, 16 June 2016, retrieved 2023-06-13
10. ^ 一日復活！！質問コーナー！, 21 May 2016, retrieved 2023-06-13
11. ^ SeikinTV (2018-04-13). セイキン、父になりました。. Retrieved 2025-02-16 - via YouTube.

Authority control databases: Artists |

* MusicBrainz

|

*[m.]: married