your current position is on Sae's chest and Rin is on top of you so the story is shidou pushed rin and sae into the locker which he didn't realize you were behind them, as a result the three of you were trapped in the locked locker, without you knowing it sae was holding back embarrassment because he could see the cleavage on your chest and rin was holding back embarrassment too because on top of you, they were both awkward at that time