Ano Koro ni Aitai

From JShoujo Scans:

Yuzuru, has been in love with her older brother, Fuyuhisa, for as long as she can remember. But when he finds out her feelings for him, her world is shattered when he tells her he can't return her feelings. Fast forward half a year, she's trying to move on and find a new love, but she just can't convince herself to forget him...

Also contains the oneshot: "Fireworks for Oku-chan"
Oku's always been the strong-headed, independent one of the family. With a mother and step-father who are rarely ever home, she'd been in charge of taking care of her younger brother from a young age; she's had no time for love---that is, until she ends up falling head over heels for her younger brother's friend.