Harem Plan

The Harem Plan is a plan that was initially proposed by Lala  and her costume robot,  Peke, to Rito after Rito's confession of love to Lala (in Chapter 162 of the original To LOVE-Ru series). However, since Rito was also in love with Haruna, Lala decided to share Rito with her best friend. In her plan, she wanted Rito to confess his feelings to Haruna (since Lala secretly knows that Haruna reciprocates his feelings too) so that they can all live happily since if Rito were to marry Lala and become king of Deviluke, Earth laws will no longer apply, making polygamy legal.

In To LOVE-Ru Darkness, it was revealed that Momo is also in love with Rito. However, Momo does not want to intervene in Rito and her sister's relationship. However, when Lala told Momo her Harem Plan, this gave Momo hope to have a compromise where Rito can love Momo as well. She creates another version of Lala's Harem Plan so that all of the girls who are in love with Rito may be happy, including her, without hurting anyone. Momo's idea is to not only make Rito marry Lala, and then have Haruna as his concubine. She wanted every girl associated with Rito that have feelings for him to become his concubines with Lala as his legal wife. The ones included in Momo's Harem Plan are herself, Lala, Haruna, Mikan, Nana, Yui, Yami, and Run. Mea, Kyouko, Rin and Dr. Tearju are also under consideration to be part of the plan. However Nemesis tells Momo to give up on the plan because she wants Rito all to herself as her servant, effectively making Nemesis the main antagonist against Momo's objective.