Momo und Nana streiten sich wegen jeder Kleinigkeit und Lala versucht die beiden Schwestern zu versöhnen, doch das leider nur mit mäßigem Erfolg. Yamis und Meas Beziehung liegt immer noch auf Eis, wobei Rito versucht Yami zu überzeugen, mehr mit ihr zu machen. Dabei denkt Rito erstmals ernsthaft über das verlockende Angebot von Momo nach...
As Lala fixes up Nana's De-Dial, Momo tells to Nana grow up while looking at her chest, infuriating Nana. Lala brings out an item that grows Nana's breasts, but it only works for a few seconds and shrinks Momo's breasts. Momo sarcastically admits that she understood Nana's feeling. Later in Mikado-sensei's office, Rito and friends discuss about Lala's inventions and Oshizu asks about Lala's childhood. Momo recalls the frequent incidents with Lala's inventions; whenever she was fighting with Nana, Lala's inventions ran wild and they both cleaned up Lala's mess.
At lunch, Rito and friends visit Mea's apartment. The apartment is empty and Mea notes that she lives alone. Nana finds it strange knowing that Yami is her sister while Momo was hoping to collect more details about master. In the follow-up meeting with Mikado-sensei and Oshizu, Momo expresses concerns about Mea and how she may be hiding her true heart. Yami notes that their hearts are incomparable with a human's heart because she and Mea are both weapons. Rito invalidates Yami's claim and relates the sibling analogy to Mikan. The meeting is cut short when a dog clings onto Oshizu, making her rip Yami's clothes, causing Yami to chase after Rito.
Afterschool, Ren gives Rito Run's CD and explains about Lala's pure sweet child personality. Rito considers it as he thinks about Momo's harem plan. Later at night, Mikan asks Rito to call Lala and her sisters down for dinner. Rito enters Lala's room and finds her fixing an invention. Rito asks Lala when she started making inventions; Lala replies that it naturally came to her whenever she got bored. Momo hears Rito in Lala's room and thinks Lala is about to kiss Rito, but rejects the theory. She and Nana listen on. Rito asks Lala about her incidents; Peke replies that they were incentives to reunite Momo and Nana. Remembering what Ren said, Rito panics as he looks at Lala and activates an invention, tying both of them up. Momo and Nana discuss how much Lala cared f
Pour Momo et Nana, toutes les occasions sont bonnes pour se disputer. Fort heureusement Lala veille sur ses petites sœurs. Momo cherche à avoir plus d'informations sur Mea Kurosaki, et demande de l'aide à l'infirmière, Mlle Mikado. De son côté, Rito, après en avoir découvert un peu plus sur Run, se pose maintenant des questions au sujet de Lala. Il décide de se rapprocher de cette dernière pour en apprendre plus sur son passé…
ララの発明品で大騒ぎのいつもの結城家。今回の発明品は、ナナのおっぱいを大きくするという画期的アイテムだった！…が、案の定欠陥品で、今度はモモが貧乳になってしまった!? そんなララの発明品がらみのトラブルは昔からのことらしく、モモは子供の頃の思い出を楽しそうにリトに語る。しかしララのトラブルの裏には、ララの妹たちへの深い思いやりがあって…。
Mientras Lala arregla el De-Dial de Nana, Momo le dice a Nana que crezca mientras mira su pecho, enfureciendo a Nana. Lala saca un artículo que hace crecer los senos de Nana, pero solo funciona durante unos segundos y encoge los senos de Momo. Momo admite sarcásticamente que entendió el sentimiento de Nana. Más tarde, en la oficina de Mikado-sensei, Rito y sus amigos discuten sobre los inventos de Lala y Oshizu pregunta sobre la infancia de Lala. Momo recuerda los frecuentes incidentes con los inventos de Lala; cada vez que peleaba con Nana, los inventos de Lala se volvían locos y ambos limpiaban el desorden de Lala. En el almuerzo, Rito y sus amigos visitan el apartamento de Mea. El apartamento está vacío y Mea nota que vive sola. A Nana le resulta extraño saber que Yami es su hermana, mientras que Momo esperaba recopilar más detalles sobre el maestro.
