Synopsys
When Zastin hears about Momo's Harem Plan, he sends one of his servants to Earth to boycott it and make Lala the only lover for Rito. The servant convinces all of the girls not to love Rito anymore, but he fails in convincing Haruna. Later, he decides to let Ren make a couple of Rito & Haruna. If Ren completes this challenge, he'll be allowed to marry Lala. When Tenjouin hears Zastin is back, she gets resolute to confess to him. But Rin keeps looking at the servant...
P.S. This isn't the synopsys for the 'planned' season 4, but another story I completely made myself. Please comment!