The choir was founded in 2015 by members of the Tokyo Metropolitan University Glee Club in 2014.
Actinia is the scientific name of a sea anemone, and the name was inspired by a comment from an audience member who said, ""The way you sing with everyone breathing together without a conductor looks like a surging sea anemone.""
They have soft and delicate sounds, and their repertoire consists mainly of unaccompanied male four-part pieces.
In addition to participating in events in Tokyo, they have also performed in Hokkaido and Osaka.
Their base of activity is Tokyo, but in recent years the number of remote members (Fukushima, Osaka, Hyogo, Fukuoka) has been seriously increasing.