Maretu (stylized in all caps), also known as Gokuaku-P (Japanese: 極悪P, "EvilP"), is a Japanese musician, Vocaloid producer, and songwriter. He started releasing Vocaloid music in 2011, and the Real Sound described him as one of the representative Vocaloid producers since 2017. He has gained a cult following.

Maretu's musical style mixes heavy metal, chiptune, and techno-pop, and he extensively uses drum patterns and Phrygian mode in his musical compositions. Another feature of his songs is the use of traditional Japanese musical elements. As an example, he incorporated shamisen and kakegoe in the B melody of SIU, applying the Phrygian mode to the Japanese-style scale similar to the mode.

Maretu's music videos often feature word clouds, and his lyrics usually tell a story related to the theme, containing depressed romantic feelings, alienation, and antinatalism. Kobashi Taiki from KAI-YOU described his lyrics as "dark and difficult to understand". Maretu always creates a disagreeable atmosphere in his work through dissonance, sound effects with profound meaning, and painful sighs.

Maretu has been diagnosed with autism, attention deficit hyperactivity disorder, and mild to moderate depression. In 2018, he admitted to cheating on his ex-girlfriend and sued her for defamation, as she alleged he cheated with someone below the age of consent in Japan.

Coin Locker Baby (Japanese: コインロッカーベイビー) is Maretu's first album, released on March 2, 2016.

FRIED EYE (Japanese: フライドアイ) is Maretu's second album, released on December 21, 2018. The album is entirely instrumental.

SIU (Japanese: しう) is Maretu's third album, released on November 17, 2019.