Houkago Kappa

放課後カッパー

Is a lyrical rewrite of Shoujoshiki Elise's song '放課後ヤッホー' from their 2019 album 'フルアルバム'. The song is set to a short animation of the character Sara Azuma from the series. She is voiced by Teiko, Shoujoshiki Elise's lead signer.