It's been announced that Tsubaki Factory member Akiyama Mao has been diagnosed with COVID-19. 

According to Up Front Promotion, Akiyama returned home to Osaka when one of her family members tested positive for the virus. As such, she conducted the PCR test and was confirmed positive for the virus as well. Due to this, she was absent from Hello! Project's concerts on January 8th and 9th at Nakano Sun Plaza Hall.