Perfume to release a new song "Flow," which is the theme song for TV series "Fight Song." The B-side track is "Mawaru Kagami (polygon wave live ver.)," a song that was eagerly awaited as a "mysterious new song" by fans at "Perfume LIVE 2021 [polygon wave]" held at Pia Arena MM last August. Comes with a bonus DVD with bonus video footage: "Mawaru Kagami (polygon wave live ver.)" at Perfume LIVE 2021 [polygon wave] - New Edit - and "Perfume View -Perfume LIVE 2022 [polygon wave]-." Special packaging (sleeve case/digipak) with a bookmark.