[2] In late 2023, the magazine Shukan Bunshun ran a story that Matsumoto had engaged in sexual assault at parties.

In early 2024 in response to the allegations, Matsumoto suspended public appearances to focus on a defamation trial against the publisher of the magazine.

[5] He has expressed his feelings about growing up in a poor household in a poem titled Chicken Rice (チキンライス, Chikin Raisu) which Hamada turned into a song in 2004.

[7] He credits his poverty for giving him a good imagination and sense of play, as it forced him to invent his own games to entertain himself.

Although he secured a job at a printing office, to pursue his dream of becoming a comedian, he was invited by Hamada in 1982 to enter Yoshimoto Kōgyō.

[1] Matsumoto remained single with no history of marriage for years after his comedy partner, Hamada, was married with children.

[13] He enjoys tokusatsu shows and owns DVD box sets of series such as Kamen Rider and Giant Robo.

On June 28, 2010, Yoshimoto Kogyo announced that Matsumoto would not be performing on any shows for two months due to an injury on his left hip, which required surgery.

[18] For two episodes, the remaining Gaki no Tsukai cast members discussed his condition,[19][20] with Matsumoto returning to hosting on August 31, 2010.

In December 2023, two women made anonymous allegations in an article published in the weekly Japanese celebrity magazine Shukan Bunshun that Matsumoto had sexually assaulted them in 2015 at "VIP parties".

[22] Matsumoto himself responded saying "I'll fight because (the allegations) are totally groundless," however he subsequently paused his comedic and hosting performances.