Martha!! has 1 A1 x J1 concert.

A1 x J1 is a hip-hop duo consisting of English rappers A1 (Phineas Waweru) and J1 (Joshua Somerkun) who met online during the COVID-19 lockdowns of 2020 and began creating music together. They released their debut single "Latest Trends" in February 2021. Peaking at number two on the UK Singles Chart, it attracted the attention of other UK rappers, including Aitch and A Boogie wit da Hoodie, who both remixed the single. Later that year, SwitchOTR featured the duo on his single "Coming for You" while A1 x J1 featured Deno in their second single "Baby." In 2022, the duo released several more singles including "Night Away (Dance)" with Tion Wayne and "Don't Lie" with Nemzzz while being featured on Mabel's "Deal or No Deal" and toured with Russ Millions in support of N-Dubz first tour in eleven years.