|Also known as||Kei-chan (K-chan), Keii-chan, Koyamacchi|
|Born||1 May 1984|
|Origin||Sagamihara, Kanagawa, Japan|
Koyama, born in Sagamihara, Kanagawa as the youngest of two children, is the oldest member of NEWS and is often seen as the mother figure of the group. Before he was in NEWS, he was a member of BAD and J-Support, which was later renamed K.K.Kity, along with fellow NEWS members Hironori Kusano and Shigeaki Kato. As the leader of K.K.Kity, he was often an announcer and this has carried through to NEWS. Despite this, he actually only joined Johnny's Entertainment at the beginning of 2001, when he was 17 years old.
Upon entering Johnny's Entertainment on January 21, 2001, Koyama started out with the unit B.A.D. which stands for Beautiful American Dream. His second unit as a junior was B.B.D. which at first stood for Bad Boys Dancing, but was later changed to Best Beat Dancing. In October 2001, he was chosen as a member of Domoto Koichi's project, J Support, alongside fellow NEWS members Hironori Kusano and Shigeaki Kato. It was in this unit that Koyama started out as an announcer for shows such as the Ya-Ya-yah Show, and this has carried through to NEWS, which he joined in September 2003.
In 2007, he graduated from Meiji University's Department of History and Geography with a degree in Oriental History. He also occasionally participates in dramas such as guest starring in his bandmate Yamashita Tomohisa's drama Kurosagi.
From 2006 until March 2011, he hosted the popular TV variety show Shounen Club (Boys Club) alongside KAT-TUN member Nakamaru Yuichi. Now he can be seen weekly as a newscaster on NTV's daily news program called "News Every".
On June 8, 2018, Koyama's entertainment career was halted. He attended a party where he gave an underage girl alcohol. The drinking age in Japan is 20 years old, and while she said she was 20 and legally able to drink, it was later discovered that she was in fact younger. This put his entire career on hold, including his entertainment activities with Johnny's Entertainment and his job as a newscaster for the program "News Every."
As of June 27, 2018, Koyama has resumed his entertainment activities. As of November 2018, his news casting activities have not yet resumed.
- Kanojo ga Shinjyatta (彼女が死んじゃった) (2004)
- Unlucky Deizu: Natsume no Bōsō (2004)
- Kurosagi (Episode 2 only) (2006)
- Ns' Aoi (Ns'あおい) (2006)
- Hana Yome wa Yakudoshi (2006)
- Yukan Club (Episode 6 only) (2007)
- Loss:Time:Life (ロス：タイム：ライフ) (Episode 2 only) (2008)
- Guests of Room 0 (0号室の客) ( 5th story ) (2010)
- Lucky Seven (2012)
- Juyo Sankounin Tantei (重要参考人探偵）(2017)
- High School Musical (2007) as Troy Bolton
- Loss:Time:Life (2008)
- Call (2009)
- Room 0 (2010) as Shigeto Oyama
- Hello, Goodbye (2012) as Kumagai Ango
- Ya-Ya-yah (TV Tokyo, 2003–2007)
- Hi! Hey! Say (TV Tokyo, 2007–2009)
- Shounen Club (co-hosts with Yuichi Nakamaru) (NHK, 2006–2011)
- Ashita Tsukaeru Shinrigaku! Teppan Note (2008)
- Soukon (co-hosts with NEWS) (NTV, 2009–2010)
- news every (NTV, 2010-ongoing)
- Mirai Theater (co-hosts with NEWS member, Shigeaki Kato) (NTV, 2012-2015)
- Karaoke 18ban (NTV, 2015)
- Chikarauta (NTV, 2015-2017)
- Hen Lab (co-hosts with NEWS) (NTV, 2015-2016)
- NEWS na Futari (co-hosts with NEWS member, Shigeaki Kato) (TBS, 2015-ongoing)
- Shounen Club Premium (co-hosts with NEWS) (NHK, 2016-ongoing)