Captain Underpants Wiki
Real Person

"Darn you, Charles Cotesworth Pinckney!" - George, Harold, and Mr. Krupp
This page is about a real life person, not a Captain Underpants character.

Koji Matsumoto is a Japanese singer, songwriter, and actor who is best known for writing the songs on the Captain Underpants album Super Silly CD o' Fun and the Extra-Cheesy CD o' Fun. Both CD's include 10 songs, plus some bonus tracks in Japanese. He has a YouTube channel called KojiUnderpants, where the music videos of his songs can be found. Although this channel has not uploaded since 2009.

His most viewed video is the video for "Super Silly Streak," which has over 200,000 views. His other biggest hits are "Captain Underpants!," "Shaking Hands," "Oops I Farted," and "The Flip-o-Rama Song." As of July 2020, this channel has 340 subscribers. He is also included on several live-action digital Flip-o-Ramas on the Captain Underpants website. He also has a personal channel simply called Koji Matsumoto, where he uploads his other songs, the newest of his songs being from 2 years ago.

Early life[]

Koji Matsumoto was born in Osaka, Japan. When he was 8 years old, he broke his leg, but he fortunately recovered a year later. He eventually moved to the United States to learn English. He most likely lives in Bainbridge Island (Dav Pilkey's hometown) today.

Relationship with Dav Pilkey[]

Koji Matsumoto was a sushi chef at a local Japanese restaurant that Dav Pilkey went to regularly in his hometown. Dav said that he met him in 1999 and became good friends with him. Koji would also make special food for Dav's dog. A few years later, Dav found out that he also had a love for music, so he asked him if he wanted to write some Captain Underpants-themed songs for his website. Before he knew it, Koji had already written 5 songs. He, Dav, and Josh Katz then began work on a couple extremely low-budget music videos for some of these songs between 2006 and 2007. This website is no longer active, but these songs are still available on YouTube and CD.