Futaridake no Kyoushitsu

From Huffly Parfait Scans:

It's the last day of school before vacation and Yuki waits for the perfect opportunity to give Koharu her chocolates and to confess her feelings for him, but she can't bring herself to do so when the classroom is still filled with her classmates!
She even pleads the curtain to conceal them and give her the chance to take the chocolates out of her bag. When will Yuki finally muster up her courage to confess? Will the perfect opportunity ever present itself?

"Original" doujinshi by the circle Milmake Orange.