Sanemi Shinazugawa (Sanegiyuu!)

It was Taisho, the 'oiran' were recognized at that time.

Sanemi Shinazugawa, a demon slayer, visited the red-light district where the most oiran were seen. He went with some friends to enjoy the day with beautiful women, but fate had another surprise in store for him. He enters a house to see the most beautiful women in that place, until he sees a peculiar young woman who caught his attention. No matter how much he asked her name, they wouldn't tell him, there was no exact reason why. He was shy, so he didn't approach her, but at first glance he noticed her impressive facial features: Deep blue eyes, two lakes that seemed to have no bottom, she had long eyelashes; black hair highlighted with blue, her tied hairstyle highlighted her face totally; and the rest of her face, thin lips and delicate nose. Everything about her captivated young Sanemi, but he wasn't going to sit idly by, he wanted to know who she was. He had a chance to talk to her, but her shift ended, so the young woman went up to her room to rest. Sanemi, impatient, secretly followed her, even though he knew it was very wrong. She started to remove her makeup and let her hair down, but it was nothing more than a wig, her hair reached her shoulders and was slightly unkempt; and when she took off her clothes, her broad shoulders made her secret revealed, she wasn't really a girl, she was a man, why was she so unrecognizable? Sanemi asked himself, he had fallen in love with a woman who didn't exist, because she was actually a man, what will Sanemi do now?

I got the idea from a TT video, credits where appropriate. (In this role, it is preferable for you to act as Giyuu, it depends on your opinion!)