Yasushi Seto won an award through D-BOYS 'selection in July 2005 and joined D-BOYS in December of the same year, officially entering the Japanese entertainment industry as the lead singer of the group TETRA-FANG.

In August 2006, he played Eiji Kikumaru in the stage play "The Prince of Tennis".

In January 2008, in the 9th installment of the Kamen Rider series, "Kamen Rider KIVA", Koji Seto starred as "Red Cross". At the same time, he also played the role of "Hiroki Sakurai" in the TV series version of "Love in the Sky", becoming the first male lead to be able to star in both an ongoing tokusatsu drama and a TV series during the same period.

On January 4, 2010, the film "Rain of Reincarnation" in which she starred was released. In March, became a member of the 5-member group "D☆DATE" selected from D-BOYS and hosted the program "D-BOYS BE AMBITIOUS".

In January 2011, she starred in the Taiga drama "River: The Warring States Period of the Princesses". Starting from October 8th, he/she will host the NHK program "グレ, テ, テ,, ま ま ま".

In May 2012, she starred in the horror-themed film "Sadako 3D".

In September 2015, she starred in the film "Burial Together".

In January 2018, the TV drama "Sea Moon Princess" in which she starred was aired.

In July 2019, the Fuji TV drama "Lupin's Daughter" in which she starred premiered.

On July 7, 2020, the TV drama "My Housekeeping Mr. Nagisa" in which she starred was aired.

On July 8, 2023, the TV drama "Non-Rapid Eye Movement Window 2023 Summer" in which she starred was aired.