"Koi" by Kitaro is performed in the key of D major. Composed and performed by the Japanese musician Kitaro, "Koi" is a serene and contemplative instrumental piece that reflects the beauty and tranquility of nature. The word "koi" itself translates to "love" or "affection" in Japanese, and the music captures a sense of emotional depth and connection. Kitaro is known for his mastery of synthesizers and electronic instrumentation, which he blends with traditional Japanese musical elements to create a unique and captivating sound. "Koi" is often associated with relaxation and meditation, offering listeners a calming auditory experience.