Hime-chan's Ribbon(1990)

Hime-chan no Ribbon

Himeko Nonohara is a tomboyish middle school student. One day, Princess Erika from the Land of Magic appears and offers her a ribbon that allows her to transform into other people in exchange for observing her for a year. Himeko immediately transforms into her older sister Aiko and runs outside. Then, her crush, Hasekura-senpai, appears...!!

(Source: MANGA MILLION)