Behind Naif's hit works, there is Pepeng who is credited as the band's songwriter and lyricist.

Franki Indrasmoro Sumbodo or familiarly called Pepeng is popular as the drummer of the band Naif.

Aside from being a drummer, Pepeng is also active as a songwriter, including the famous "Posesif" taken from the album Jangan Terlalu NAIF (2000). In addition, he also designed the cassette/CD covers of The Best of NAIF and Retropolis (2005), as well as conceptualized and produced NAIF's video clip Jikalau (Titik Cerah album, 2002) and the five videoclips in the Retropolis album.

Apart from NAIF, Pepeng also has another music project, Raksasa. The band consists of Pepeng (drums), Adi Cumi (vocals) from Fable, Iman Fattah (guitar) from Zeke And The Popo, a soloist with the Delta Blues genre Adrian Adioetomo (guitar) and Adhi Tomo on Bass. Another music project is Frank N' Friends, where he acts as a writer and producer as well as a musician. FNF itself is the latest music project that Pepeng is still running to this day.