limited to 6,940 copies total. Each one was written by a different band member and released at a concert held on the 40th birthday of its songwriter. The three-date Lock on Snipe Tour #9 took the band to Shanghai and Taipei in December. On December 28, Mucc presented Trigger in the Box at Yoyogi National Gymnasium. It featured other acts such as Hyde, 44 Magnum, Ling tosite Sigure, and Oldcodex. From January 10 to February 9, 2020, Mucc performed the Lock on Snipe Tour #10. Due to the COVID-19 pandemic, they had to cancel April's Lock on Snipe Tour #11 in Europe and their June 21 concert at Pia Arena MM. They contributed a cover of "Mezmerize" to the May 13 Granrodeo tribute album Rodeo Freak. The band released the made-to-order single "Shōfu 2020", which contains four different recordings of their first single "Shōfu" from various points in their career, on June 9 to celebrate its 20th anniversary. Mucc's fifteenth studio album Aku was released the following day. They held ~Fight Against COVID-19 #2–3~ "Aku - The Broken Resuscitation" no-audience live streams on June 21 and September 20. Their December 27 show at the Nippon Budokan was the band's first concert with an audience in 10 months. On December 2, 2020, Mucc announced that Satochi, who had been their drummer for 23 years, would be leaving the band in spring 2021 and cease activities as a professional musician. His last tour with the band, Mucc Tour 202X Aku - The Brightness World, began in February 2021, but its final four shows were rescheduled to August after Japan declared a state of emergency as a result of the pandemic and Satochi tested positive for COVID-19. The final two concerts were postponed again due to the pandemic and took place on October 2 and 3 at The Hirosawa City Hall in the band's home prefecture of Ibaraki. The compilation album Myōjō was released on April 21 during the tour. All of its songs were either composed or co-composed by Satochi, with four of them newly re-recorded, while the lyrics to the new title track are credited to the whole band. A day after Satochi's departure, Mucc released new artist pictures showing them as a trio. The double A-side single "Goner/World" was released in November 2021. 2022 marks the 25th anniversary of Mucc's formation. They began celebrating with an acoustic live on May