ONGA PROJECT is an official derivative music project based on the concept of "Music x Manga = Onga (Sound Picture)," combining manga source material with creative inspiration to expand and accelerate the possibilities of manga. For this 11th installment, Mashiro Shirakami handled lyrics, composition, and arrangement, while Shota Horie (kemu / PENGUIN RESEARCH) served as producer.
Yanagi Nagi began her music career in 2006 and has established herself as a prominent figure in the anisong scene through her work as a guest vocalist for supercell and numerous anime theme songs. She released her 7th original album "White Cube" in March 2024.
Mashiro Shirakami is active as a singer-songwriter, track maker, and bassist, and became a director of PHYZ Inc. in 2025. Producer Shota Horie is also known as the Vocaloid creator "kemu" and serves as the bassist of the band "PENGUIN RESEARCH." He founded PHYZ Inc. in 2025 and serves as its CEO.
"Mamahaha no Kokoroe" is an isekai child-rearing fantasy by original author Toru, artist Hoonoki Sora, and story composition by Fujimaru Mamenosuke. The story follows a protagonist who is reincarnated as the villainous stepmother character from a manga she was reading, and her struggles to care for her adorable stepson. It won the grand prize at Comic Seymour's Electronic Comic Awards 2026.
To celebrate the music video release, a limited-time campaign running from July 1 to July 14, 2026 offers the manga version Volume 1 for free, 6 serialized volumes for free, and the light novel version with 2 volumes free plus 30% off.
■Music Video
https://youtu.be/8uofZSoZH9w
■Credits
Vocals: Yanagi Nagi
Lyrics/Composition/Arrangement: Mashiro Shirakami
Producer: Shota Horie (PHYZ)
■Original Work
"Mamahaha no Kokoroe" (AlphaPolis)
Original: Toru / Art: Hoonoki Sora / Composition: Fujimaru Mamenosuke
©Toru, Hoonoki Sora, Fujimaru Mamenosuke / AlphaPolis