Love this ship, though I kinda hate how Rika acts in the game in some of the other girls side stories (Mamis), though I get that its just a defense mechanism. Hope their relationship progresses more in the game.
I like to think that that part of Mami's sidestory was before Rika met Ren. Otherwise, Mami might need to be careful of a certain scythe-wielding magical girl the next time she's alone in Kamihama.