Thankfully there's nothing really like that! I am gonna info dump a little on though just to make sure since I am also super blind to your canon outside of what's in here.

Yukine (Ren) is a shinki, meaning he was a wandering pure spirit of a dead human who was murdered or killed in an accident such as a car crash or something. In Yukine's case, it's been hinted at that he was murdered by a family member because his unlife can never be hard enough. Impure spirits would be someone who took their own life. Shinkis are made when a God finds them and names them as their vessel and can only be made out of pure spirits.

So, Yukine's name is tattooed on his collarbone. He belongs to Yato who is a god of calamity. He turns into a sword on his command.

As a shinki, he's a being who exists on a plane between the human world and heaven. So he sees humans, other spirits, phantoms (corrupted spirits), and gods and humans have difficulties with seeing him and remembering him after they do see him. The point of his existence is entirely to humanise the god he serves since he used to be a human and understands things like sin where as a god has always been a god. Annnnd to remain pure because his impurities and sins can damage the god he serves (this is how Yato imagines it, the words are true but Yato's mental image of greatness are false. Reality: Yato's trash in a tracksuit and Yukine's job is to beat him until he does work).

For him, heaven is pretty much the bureaucracy that controls gods and their shinkis. It's a weird place, can't imagine it's anything like Kevin would know it.

eta: As a shinki, he retains no memory of his life as a human. Not even his name.