Human sweat have oiliness, which stains white clothes. For an example, my school uniforms, which were white and made of a cotton polyester mix, always had stains because I was sweating profusely because I live in a tropical country and classes are open from both sides with 2 fans fir the whole class. Uniforms are always sent to laundry for spot cleaning after the term end. They were discarded after an year of wear, not only because I was growing taller, but the clothe after being constantly washed, was becoming thinner. We had 2-3 or more uniforms to wear. This guy had one shirt and it's washed without soap. That shirt irl would be see through, yellower and full of mysterious stains.
I was wrong in my previous reply in 2021 to say a better man would wait. No no no. A better man wouldn't even consider the possibility. A better man would find a peer of an age close to him as a life partner.
Also Teen boys are gross and the least attractive thing to an adult man and Kousuke is a fucking pedo.

That white shirt he was wearing must now be musty