[1] Yonehara debuted in 2001 as a member of the boy band and acting troupe Run&Gun.
As an actor, Yonehara has appeared in stage productions such as Air Gear, Fruits Basket, and Peacemaker Kurogane.
!, where he was selected as one of the members for the boy band Run&Gun,[2] later debuting on July 4, 2001 with the single "Lay-Up!
"[3] During his time with the group, in 2005, Yonehara also released a solo song titled "Memories" for Run&Gun's first extended play, Hateshinai Tabi no Naka de...[4] As an actor, Yonehara appeared in the stage adaptation of Air Gear as Hamlet, but in the second installment he took over the role of Romeo from Ryuji Kamiyama after he had replaced Kenta Kamakari (who had fallen ill) as Minami Itsuki.
He also played the female role of Rosemary in several Maria Magdalena stages.