Look at Mary's shy-like gesture and slight smile. Look at Ayano's absolutely embarrassed pose! (because she realized that the artist drew her breasts slightly larger than usual) As a decent human being, she's not used to wear really revealing clothes on public with others (including friends). She must've hated warm beach sunshine hitting her upper body just because she forgot not to wear trademarked red scarf. Nevertheless, twintail braids really suit Ayano-chan adorably!