Yokoyama entered Johnny's on Christmas 1996 where he met fellow members Subaru Shibutani and Shingo Murakami.

The reason he entered Johnny's is because his mother briefly saw his classmate on TV and said, "My kid is better looking."

When appearing in variety shows and radio, Yokoyama and Murakami are the two most talkative members.

He rarely speaks whilst in the dressing room, as he is too busy playing games.

Recently, Yokoyama has been appearing in quite a few dramas such as The Quiz Show 2 and Hidarime Tantei EYE.