|Born||March 8, 1978|
|Debut Single||Ai wa Muteki ~Hatachi no Yoru no Chikai~|
|Last Single||Ai wa Muteki ~Hatachi no Yoru no Chikai~|
|Left||February 1st, 2002|
Upon joining Sheki-Dol in 2001, Arai Saki said in an interview that she had always loved singing since pre-kindergarten times, and always wanted to be a singer. When she was 20, she had the opportunity to take part in an audition. At the audition center, one of the judges had asked her if she was interested in coming to Tokyo to join an agency. She left for Tokyo the next day to meet up with the agency, and after an interview decided to move to Tokyo. It was the same agency as Amuro Namie's.
She started doing small jobs such as modeling, talent work, photo shoot for magazines, being a spokesperson for a cosmetic product, and a TV commercial, while paricipating in auditions in between.
In December 2001, Sheki-Dol released their fourth single Ai wa Muteki ~Hatachi no Yoru no Chikai~.
In January 2002, shortly after Arai Saki's debut in Hello! Project, it was announced that Sheki-Dol was going to disband. She left Hello! Project and the agency alongside the other members after the group's disbandment.
In 2004, Arai became a campaign girl for BoatBoy, and frequently promoted the campaign at their blog. The blog has not been updated since 2006.
In 2007, she went to Russia to study the language and updated her personal blog regularly until 2011.
In 2009 Arai Saki married retired Urawa Red Diamonds football player Horinouchi Satoshi.
- Name: Arai Saki (荒井 沙紀)
- Legal Name: Horinouchi Saki (堀之内 沙紀)
- Nickname: Sakippo
- Birthdate: March 8, 1978
- Birthplace: Osaka, Japan
- Blood type: A
- Height: 159cm
- Western Zodiac: Pisces
- Eastern Zodiac: Horse
- Hello! Project Groups:
- Sheki-Dol (2001-2002)
- She can speak Russian and Korean.
- In 2007, she studied abroad in Moscow, Russia.
- Formerly a campaign girl for BoatBoy.
- Released the single ypa☆pa in Russia.
- She has two sisters
|Members||Kitagami Ami | Oki Ibuki | Suenaga Mami | Arai Saki|
|Indie Singles||1. Kokoro no Pheromone | 2. Tetteiteki Unmei | 3. Zentaiteki ni Daisuki Desu.|
|Major Singles||1. Ai wa Muteki ~Hatachi no Yoru no Chikai~|