@NinjaGoemon and
@MidnighTea: The manga generally sexualizes (female) Matsuri more than the regular girls. We've seen him undressed the most by far, and he's the only one with visible nipples (just look at chapter 11), even if they're airbrushed outside the volumes. In the chapter after this, the octopus grabs Suzu by the waist and wraps around her leg, but it doesn't strip her, grab her breast, or spread her legs apart like it did to Matsuri.
Most of it I'm fine with, and the nipples thing is kind of funny. Matsuri getting
groped more because he identifies as male is pretty messed up, especially when he explicitly
doesn't think being a guy means he should tolerate being sexual harassed. (I likewise am particularly fond of Matsuri as a character, which makes it more painful.)
That said, "Matsuri is sometimes sexually humiliated, even though other girls aren't" is definitely the lesser of two evils if the other option is this stuff happening regularly to
all of them. People defending (or even condemning) ecchi often miss the difference between complaining about any kind of sexuality versus fetishized sexual humiliation and such.