Two years have passed on the peaceful island of Hatsune. One evening a mysterious girl appears on Asakura Jun'ichi's doorstep, looking for Jun'ichi's grandmother, who only recently died. Since she has nowhere to go, Jun'ichi decides to take her in.

When Asakura Nemu, Jun'ichi's non-blood-related sister, returns after two years of study at Nursing College, she is very much surprised to find her brother living under the same roof with this new girl. Nemu now works as trainee at Kazami Academy's infirmary, Jun'ichi's school. A few months later, Yoshino Sakura, also gone for two years, returns.

But who is this new girl and what connection does she have to the ever-blooming sakura on Hatsune Island?