Septimus’ Kindness?

The moonlight flowed over Septimus like a river of light, outlining his slim body figure and dying the air particles white. Seeing the man's refusal to respond to her statement, a sardonic smile flitted across the tip of her lips. 

"Why do you look so surprised? This isn't rocket science." Lin Sanjiu smirked. She straightened her back as a card appeared in her palm. "After meeting Ryuji, the staff working in Mokugyo Forum, I already knew the person behind this manhunt must be one of Luther's twelve personalities. Besides, you have a rather distinctive characteristic, so…"

When she was in Oasis, 12 had deceived Marcie into thinking that he was Septimus. During that time, she learned that "Septimus" had a gender identity disorder.

Instinctively, Septimus lifted his hand and ran his fingers across his collarbone.