
Quick answer — BLUE ENCOUNT performed 2 anime themes, including "DAYxDAY" from Gintama Season 3, "My Hero Academia Season 4 Opening 1 | Polaris" from My Hero Academia Season 4.
BLUE ENCOUNT performed the anime theme songs "DAYxDAY" (Gintama Season 3), "My Hero Academia Season 4 Opening 1 | Polaris" (My Hero Academia Season 4).
BLUE ENCOUNT's first listed anime theme is "DAYxDAY", the opening of Gintama Season 3.