Five Minute Summer 32 2:03:72

You are able to hold it off for a while - but then it becomes unbearable again. Well, it's only natural, thinking that Chihaya who shared you her air had been underwater as long as you are. The only difference is whether you are able to tolerate the CO2 buildup in your lungs and keep on squeezing out oxygen from your air, until it becomes completely stale. And that takes a lot of training. Discipline. And maybe gift. "Glub...glubbb!!!" And here they go.

Seeing that you had blown out the air you were given, now Aya comes to the rescue - and her face is blush, although you are not sure why. Is it from her breathold, or from what she is about to do to you? And Chihaya awaits patiently, waiting to for her second turn of air sharing.

"God please spare me," you think. "I come from land, and am neither the super-humans nor the mermaids like you are!!!"  
But you are now completely at their mercy, just like you had kept them at your mercy only earlier in the day. And you wonder, if you are really able to see the sun and feel the ocean breeze once again - after making it through this endless Five Minute Summer.