One night.
I opened the bathroom door thinking I'd take care of something before taking a bath -

"...Ah..."

Sumire was there.
Usually, she showed no anger or embarrassment,
and just waited expressionlessly for me to close the door...

But this time...it was different...
She had lost her expressionless, unresponsive personality, and not only was she embarrassed, but something abnormal had occurred.
I realized this and couldn't take my eyes off her.

That's because Sumire was clutching my underwear and masturbating while smelling it.

[From Getchu]