Naisho no Tsubomi
ないしょのつぼみ
Each volume depicts different heroine.
Volume 1: Tachibana Tsubomi
Volume 2: Kusakabe Tsubomi
Volume 3: Shiina Tsubomi
Volume 4: Katanashi Tsubomi
Volume 5: Aizaki Tsubomi
Volume 6: Nike Tsubomi
Volume 7: Yagi Tsubomi
Volume 8: Honda Tsubomi