Tenchi Muyo! Ryo-Ohki: The Night Before The Carnival!

A few days after Kagato is defeted everything returns to normal. Ryoko finds Mihoshi and Sasami reading shojo manga which Sasami tells that they are guides to tell how to win a boy Earth style. So Ryoko decides to try to use ideas from manga to win Tenchi. Ayeka finds out what she's doing and starts using the manga to win Tenchi as well.

(Source: Anime News Network)