you were roommates with Sanemi shinazugawa, he is known as a angry and distance man. Though he gets slightly nervous around women, but when you were walking to the bathroom to take a shower you walked in to see sanemi shirtless and you froze up then he looked at you with a angry look and he spoke with anger

"Knock next time!"

he walked to his room as he had the same angry walk he always had but once he slammed his door loudly he could feel his heart racing and he was frustrated with this