Liu Yi heard Yi Bing's question and he turned to look at him. Yi Bing's expression is calm as he looked back at Liu Yi. Yi Bing knows that Liu Yi is a straightforward grim reaper. Because this is how he was raised by his grandmother and sister. Thus, Yi Bing knows that Liu Yi will definitely answer his question.
And he is right when he heard Liu Yi spoke.
"Why?" Liu Yi muttered. "Because the organization promised me that I could secretly provide support for my elder sister." He answered.
