Yuzo Koshiro (古代 祐三 (こしろゆうぞう) Koshiro Yūzō?), also known as YK-2, is a Japanese video game music composer, arranger and audio programmer. He is often regarded as one of the most influential innovators in chiptune music and video game sound design. He has produced music in a number of genres, including various electronic genres (such as breakbeat, electro, hardcore, house, jungle, techno and trance), experimental, classical, hip hop, jazz and synth-rock.

He worked with Michiru Yamane on Castlevania: Portrait of Ruin Original Soundtrack.

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