Hinami deliberately changed how she addressed Byakuya—from "Byakuya-niichan" to simply "Byakuya"—because she no longer wanted to be seen as just a little sister.
"..."
Faced with such a direct confession from Hinami, Byakuya was momentarily stunned.
After all, over all these years, he had gradually come to see her as a real little sister.
Hinami was certainly beautiful and adorable, but when he first met her, she had been far too young. He couldn't possibly have developed those kinds of feelings.
Before he knew it...
Hinami had already grown into an adult. But Byakuya wasn't about to suddenly change how he saw her, which meant he wouldn't develop feelings different from before.
At that moment, Byakuya came back to his senses and parted his lips to speak.
Just as he was about to respond to Hinami, she suddenly reached out and pressed a finger to his lips.
"Actually, I'm not mentally prepared yet. How about Byakuya-niichan gives me an answer in a couple of days..."
At this crucial moment, Hinami retreated.
She had witnessed too many boys' confessions before, each time being rejected by her on the spot. The various looks of dejection on their faces afterward had left a deep impression on her, etched vividly in her memory.
So she couldn't help but feel nervous and anxious, even wanting to back out...
She was afraid of being rejected by Byakuya, and wasn't mentally prepared for rejection, since this had been an impulsive confession.
But at that moment, Byakuya grasped her hand and moved it away.
He looked at her seriously. "There's no need to wait a couple of days. At a time like this, I absolutely have to give you a proper answer."
"Byakuya-niichan..."
Shaken by his gesture, Hinami unconsciously reverted to the familiar form of address she was most accustomed to.
"From the day I met you—no, more accurately, from the day I first knew of you—I never wanted you to be hurt. So..."
Byakuya held both of Hinami's hands, his voice calm but every word sincere. "I want to make you happy."
The reason for that emphasis in the first half was because Byakuya's "knowing" Hinami and "meeting" her hadn't happened on the same day...
He had known of her before transmigrating, and met her after...
"Byakuya-niichan, does that mean... you're willing...?"
Byakuya's heartfelt words filled Hinami with both surprise and joy.
"Of course I'm willing. If I refused, wouldn't that make Hinami sad?"
Byakuya smiled.
"That's not the point. I'd rather Byakuya-niichan genuinely likes me, not just feels sorry for me..."
Though Hinami was overjoyed, she still mumbled, "Otherwise it's no different from being treated as a little sister... I don't want to be seen as just a sister..."
Though she was having trouble breaking the habit of calling him "Byakuya-niichan"...
"About that—I really do like Hinami. It has nothing to do with pity."
Byakuya said without a hint of embarrassment.