After going viral on the video-sharing platform TikTok, the song was released to urban radio by Hot Girl Productions and Warner Music Group as the album's fourth single on July 30, 2024.

[1][2] In response, Megan posted several TikToks of herself following the dance trend, including one of her cosplaying as the anime series Sailor Moon's lead character Usagi Tsukino.

[7] Its title refers to a mamushi, a type of snake mainly found in Japan, which continues the snake-related imagery and metaphors in Megan's previous singles "Cobra", "Hiss", and "Boa".

The first half of the chorus is spoken by Chiba in Japanese, who raps "Okane kasegu, orera wa sutā" (お金稼ぐ 俺らはスター), which is translated as "We make money, we are stars."

[12] Mankaprr Conteh of Rolling Stone commented "Though 'Mamushi,' with its simple beat, repetitive hook, and choppy cadence, isn't as exciting as its counterpart, it may be an important signal to her international fans and sign of her passions (plus, it has a pretty cute TikTok dance routine taking off)."

[7] Some critics had a more favorable view of "Mamushi" than "Otaku Hot Girl"; Alphonse Pierre of Pitchfork wrote "The better song that leans into her fondness for Japanese culture is the multilingual 'Mamushi,' which pulls off the theme without flattening her personality.

"[14] Lucas Martins of BPM stated "The mid-tempo 'Mamushi' executes the idea much better, as the off-kilter approach to the hook and her interplay with guest rapper Yuki Chiba allow her to make what would otherwise be a rather stiff song really come alive.