Masahiro Yamanaka is a Japanese voice actor and narrator born on December 22, 1980, in Saitama Prefecture, Japan. He is affiliated with the talent agency Kenyu Office. Standing 169cm tall with type O blood, he is also known by the nickname "Mappy".

Before pursuing voice acting, Yamanaka initially aspired to become a manga artist or illustrator and specialized in visual arts during high school. However, just before graduating, he decided to change his career path. He is a graduate of the Talent and Voice Actor course at the Chiyoda Institute of Technology and Arts. He began his professional career in 2005, debuting in the anime Play Ball. Early in his career, he was associated with Office Kaoru and the training school Talk Back before joining Kenyu Office.

Yamanaka has built a prolific career spanning television animation, video games, drama CDs, and film dubbing. His voice is described as a tenor, allowing him to play a wide variety of characters. In anime, he is known for several roles. He played Wales Tudor and Reynald in the The Familiar of Zero series. He also voiced multiple characters in the 2011 adaptation of Hunter × Hunter, including Owl, Motalike, and Pike. Another early role was Soichi Jonouchi in Kimi ni Todoke. He is also the voice of Kanade Tsukishiro in the Tsukiuta and TSUKIPRO the Animation franchises. Other notable anime credits include Gonz in Banished From The Heroes' Party, Issa Kizuku in VazzRock the Animation, and Fukurokouji in Demon Prince Enma. He also appeared in series such as Yarichin Bitch-bu as Koshiro Itome and in short-form anime like Even a Dad Still Wants It as Koya Asumi and XL上司.

Beyond anime, Yamanaka is highly active in drama CDs, particularly in the Boys Love genre, where he is frequently cast in lead roles. He also contributes to video games, with roles such as Sadamune Kikko in Tōken Ranbu, God in the game GALTIA, and Winston in the Japanese dub of Overwatch. His work extends to narrating television programs, including the long-running show Miracle Experience! Unbelievable, and dubbing foreign films and series.

Throughout his career, Yamanaka has developed recurring collaborations with fellow voice actors. He has frequently worked with Takuya Sato and maintains a close professional relationship with Yoshihisa Kawahara. He is also part of the music and performance aspect of multimedia franchises like Tsukiuta and VAZZROCK, performing character songs. For adult-oriented games and anime, he uses the alias Masato Kawamura. His hobbies and skills, which include cooking, pencil sketching, and music composition, reflect his creative background.