To Love-Ru

It is another typical day in the Yuuki household, with Momo sneaking into Rito's bed, Lala having accidents as she gets out of the bath, and as Rito gets to school he has another accident with Yami, who is convinced to show him mercy by Lala. As the school day ends, Nana offers Haruna an energy drink from Deviluke, as Momo talks to her about how she should confess her feelings to Rito, and how it need not be a competition with the other girls as polygamy is actually a common practice in the galaxy at large. Momo identifies Haruna as being the key to the "harem plan". The energy drink Haruna was drinking makes humans drunk as if with alcohol, and Rito is pressed into bringing her home just as she starts to become seriously intoxicated. When they arrive at her house she strips down to her underwear and embraces him, continuing to talk about how girls who love a guy would want to make him her own, and very nearly confesses her love, except she sobers up at the last moment just as her sister arrives.

Rito once again becomes the victim of one of Lala's inventions, which turns him into a mouse. He runs around the school frantically, trying to find her, causing mayhem wherever he goes, although the girls who like him find his mouse form inexplicably cute. He winds up falling into Yami's clothes and winds up pulling off her panties in an attempt to escape, and Mea finds him, at which point he turns back into human form, and Yami once again beats him senseless for the offence. Later, Rito sees Mea dressed in battle gear at the rooftop and he goes to see her, despite Momo's earlier admonition to avoid being alone with her. She uses her powers to control him like a doll after he suggests that her master might be wrong, but she releases him after he says he feels her feelings of uncertainty and loneliness, but that she need not be alone. They are attacked by a group of aliens who have been told Mea's location by Nemesis, which Mea interprets as being a reminder of her nature as a weapon, and as they cross the town in battle Nana sees her in her true form, with blades ready to kill.

Nana is shocked to see Mea with all her weapons out, believing that she was just an ordinary girl, and is crushed when Mea tells her that their friendship has always been just an act. Rito visits her in the virtual space where the alien animals she summons dwell, and he consoles her, embracing her and telling her about his experience of Mea's feelings of uncertainty and loneliness, and that even if she was faking everything and lying to her about her true nature before, now that she knows the truth, that is only an opportunity to become closer to her. Nana then seeks Mea out, using one of the animals Mea played with before to sniff out where she was. Mea attacks her, but she comes forward unafraid, as Mea cannot seem to make her weapons hit. Eventually Mea pulls Nana into her Trans world, here Nana manages to break through to her. Later, Mea is visited by Nemesis, who says that she can do as she pleases for now, as it is helping her to understand what led Yami astray.

The town of Sainan is bustling as a fireworks show approaches. Nana sets out with Mea, and Lala with Haruna and her friends, to the shrine to enjoy the festival, while Momo spends the time alone with Rito and feels her love for him surface again. Then Mikan, who should have been with Tearju, comes running to Rito in a panic...

Rito encounters Yui on a train, and feels extremely awkward after having run into "trouble" with her the previous night. The train grows more crowded and the two find themselves squeezed precariously close together... Later that night, Mea joins the Yuuki household for dinner at Mikan's invitation.

Rito and Momo end up alone together as they walk home from helping Rito's dad. Momo's mind fills with sweet fantasies, but then Nemesis appears and drags Rito away to play. Not only has Momo lost her alone time with him, but now Nemesis is trying to convince Rito that she can't be trusted! That night, someone walks in as Rito is bathing, and who he thinks is Momo turns out to be...

Tearju takes over as the homeroom teacher for Yami's class, 1-B. It bothers Rito and othe others to see the awkwardness remaining between Tearju and Yami, as well as Mea still resisting Tearju. Rito tries to get Yami and Tearju to make peace, but Yami is obstinate, and his words fall on deaf ears. Then Mea, touched by Rito's concern, confronts Yami, and her words lead her older sister to a decision...

Rito and the girls have come to the Tenjouin mansion to help as servants for the day. Momo, Yami, Nana, and Mea do their best in maid costumes, while Rito gets into "trouble" time and time again with Saki and Rin! In the middle of it all, Rin lunges at Rito wielding a strange sword: the demon sword Bladix, which possesses its human wielder and seeks blood. So Rito takes action to save Rin...

Lala thinks about how to get Haruna closer to Rito, but Peke tells Lala she should worry about her own relationship with Rito first. Momo, prioritizing Lala as the first wife in the Harem Plan, decides to give Lala a lecture on love using a dating sim game. That night, Lala appears while Rito is in the bath and asks him for the "special kiss" that people who love each other share...

Nana, the late bloomer in love, is left in turmoil after Momo tells her about the Harem Plan. Even Mea thinks the plan sounds fun, but an outraged Nana continues to oppose it. Then Celine shows up riding on Go-Go Vacuum-kun A, a cleaner machine Lala invented... but after being startled by Mea, Oshizu's psychokinesis causes Vacuum-kun to malfunction and go berserk, sucking up students' clothes! Rito and Nana try to stop it, but the damage only continues to spread...

When Rito tells Yami he wants her to be happy, including in her relationship with Tearju, her heart begins to waver. When Momo learns of this, and sees how his sincerity has made even Nana and Rin take interest in him, she is again convinced that he has what it takes to be a harem king.

Yami has awakened as the forbidden organic weapon, Darkness, with a goal like nothing Yami would even dream of... Meanwhile, Mea struggles to escape her bonds within the realm of Nemesis's mind. One by one, Rito's friends fall victim to Darkness, and then she finally catches up to Rito himself! Then, just as Darkness's blades draw near...