Saku-chan to Nozomi-kun

Onodera Saku posed as a boy up until the end of elementary school in an attempt to console her mother, who tremendously grieves the death of her elder brother. Seated right next to her, on the other hand, is Nishioka-kun who grows out his hair beyond the usual length for boys and because of that is picked on. Following a conflict with his classmate though he decides to cut it short. Next day he helps her when her toilet bag is snatched away by that very same boy. Fast forward. Saku-chan no longer dresses like a boy and finally confesses her love to Nishioka-kun but is rejected. How did it turn out this way?