It's New Year's and the students of the Lillian Girls' Academy are ready to celebrate a fresh start. Sei tells Yumi about the Yamayuri's annual New Year's Party, but not about the surprise she has planned.
Yumi and the others are supposed to throw a special party for the graduating third-years, but they've forgotten until the very last minute! With a celebration to plan, a performance to practice, and a growing to-do list, Yumi is in danger of collapsing under the pressure.
Graduation day arrives and brings with it a flood of emotions. As the rest of the Yamayuri Council struggle to cope with their feelings, the Rosas reflect on memories of where it all started.
Shimako just hasn't been herself recently, and Yumi is worried. She asks Sei to visit her former soeur to cheer her up. Meanwhile, Shimako's chance meeting might bring a new friend into her circle.
Shimako and Noriko become even closer, but a shocking revelation about Shimako's true religion is announced in front of the entire school, which tests their relationship. Meanwhile, the Yamayuri Council is concerned over the state of Shimako's well-being and decides to take matters into their own hands.
It's time for Shimako to select her petite soeur, but she is caught between her loyalty to the Yamayuri Council and her desire to protect Noriko. Finally, a fight forces her to make a choice.
Yumi hasn't been able to spend much time with Sachiko, who always seems to be busy with Toko. As the distance between them grows, Yumi worries her soeur is moving on to someone new.
Yumi struggles to find her identity outside of being Sachiko's petite soeur. Soon, she gets a helping hand from an old friend, a new friend, and a mysterious lady.
Yumi finally learns why Sachiko has been keeping her at arm's length lately. But now that the truth has been revealed, Yumi must decide whether the distance brought on by her soeur's dishonesty can ever really be bridged.
