Indeed, it's the print on their skirts, it's Escher inspired, with parts actually from his paintings. Gotta love it when artist put that extra detail in there.
Meari-san, I believe our bet is that whoever loses the gamble shall obey any order given from the winner, yes...?The way you tremble so much is just cute.N-no...Don't worry, it'll only hurt in the beginning.My, some cute underwear you have there.Y... Yumeko... This is... impossible...That is why starting now I'll violate Meari-san's p○ssy to my heart's content.