Sankakkei no Kowashikata

Koto, Aya, and Erika were secretly in love with each other.

Koto revealed her feelings for Aya, but a short while later, Aya disappeared as if she had been spirited away.

Seven years later, Aya reappears to Koto and Erika, just as she was then...

(Source: U-Next, translated)