Man, I just fucking hate rivals in yuri mangas
If this manga keeps progressing Tamamon's and Hina's relationship through this dumbass rival, I think I'll just drop this manga
I'm so tired of this retarded trope
It's not really a love rival, though. That much is obvious from the previous chapter. Mariru is just proving herself as a model/cosplayer/etc. because she respects Tamamon's artistic ability.