When I was taking a bath with my sister-in-law, the shower suddenly hit my sister-in-law, soaking her uniform! I accidentally got an erection while admiring her transparent body curve and underwear! I did it! When I was in a hurry, my sister-in-law was flustered and fidgeted, creating an awkward atmosphere! And my sister-in-law suddenly approached me with wet eyes! Huh! A little! I reached into my crotch! My sister-in-law and I have a secret that we can never tell our parents because of the sudden erection.