Mitsuru Adachi
is a high-school romance manga by Mitsuru Adachi. It was published by Shogakukan in 1979–1981 in the magazine "Shōjo Comic" and collected in five tankōbon volumes. It was later adapted into a live-action television drama series, an anime television series, and an anime film sequel to the television series. The title translates roughly as "What a Sunny Day!"