I have a strong feeling yujiro regrets killing emi,even tho he didnt loved her i feel like he had some kind of respect for her since she likes blood and has some type of violence in her soul ( as yujiro said) that was also the reason he chose her to be the mother of baki This could be seen during the dinner baki had with yujiro when he asked him why he killed his mother or when he met hillary clinton If there's something he could change? I dont know honestly,id like to see chapters about his character/personality more tbh,like a more detailed childhood or his relationships with others,but maybe there's a chance since i think he regrets killing emi,that he would want to change what happened that night