If i'm not mistaken tian cai parents are alive but they both were sent to the hell. His aunt also a devil and took care of him. Look at the panel when she said "grab your bottle (milk), we're going to the bar". Despite being a devil she keep taking good care of him and the previous flashback chapter she said "forgive me brother, we'll see in the hell" something like that. It implies the aunt devil can't keep tian cai anymore so he sent him to the angel society. Well we all know angel suppose to not do bad so she thought tian cai would safe there. But never did she image that those world was too cruel to tian cai.
But if u look at chapter 62, the aunt said that the uke father and dad are already dead. Idk which chapter said that they were send to the hell...and the aunt said that she want to apologize to her brother at hell means maybe if she died later she want to apologize at both of them for abandoned their child at orphanage and the aunt might think that both of them is already dead plus maybe the devil community thinks that both uke parents and the baby is already dead but actually they are still alive and hiding at others planet. The glimpse of that red long hair may be the uke dad because the uke said his dad give him the doll before the aunt take him and the uke father is an angel. It just my hunch lol.
I think the uke parents is still alive!!! I hope so (๑•ㅂ•)و✧maybe Taiya will find the info about the sender from that planet.